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                                                                    Exhibit 10.1

                                    AGREEMENT

AGREEMENT made and entered into in New York, New York, by and between
Antigenics, Inc. (the "Company"), a Delaware corporation with a principal place
of business at 630 Fifth Ave. Suite 2100 New York, NY, and Roman Chicz (the
"Executive"), effective as of the 26th day of July 2004 (the "Effective Date")
(the "Agreement").

WHEREAS, the operations of the Company and its Affiliates are a complex matter
requiring direction and leadership in a variety of arenas;

WHEREAS, the Executive is possessed of certain experience and expertise that
qualify him to provide the direction and leadership required by the Company; and

WHEREAS, subject to the terms and conditions hereinafter set forth, the Company
therefore wishes to employ the Executive as its Sr. Vice President of Research
and Pre-Clinical Development and the Executive wishes to accept such employment;

NOW, THEREFORE, in consideration of the foregoing premises and the mutual
promises, terms, provisions and conditions set forth in this Agreement, the
parties hereby agree:

1 Employment. Subject to the terms and conditions set forth in this Agreement,
the Company hereby offers and the Executive hereby accepts employment.

2 Term. Subject to earlier termination as hereafter provided, this Agreement
shall have an original term of one year commencing on the Effective Date hereof
and shall be automatically extended thereafter for successive terms of one year
each, unless either party provides notice to the other at least ninety (90) days
prior to the expiration of the original or any extension term this Agreement is
not to be extended. The term of this Agreement, as from time to time extended or
renewed, is hereafter referred to as "the Term of this Agreement" or "the Term
hereof".

3 Capacity and Performance.

(a) During the Term hereof, the Executive shall serve the Company as its Sr.
Vice President of Research and Pre-Clinical Development and shall report to the
Chief Executive Officer. In addition, and without further compensation, the
Executive shall serve as a director and/or officer of one or more of the
Company's Affiliates if so elected or appointed from time to time.

(b) During the term hereof, the Executive shall be employed by the Company on a
full-time basis and shall perform such duties and responsibilities on behalf of
the Company and its Affiliates as may be designated from time to time consistent
with his position as Sr. Vice President of Research and Pre-Clinical
Development.

(c) During the Term hereof, the Executive shall devote his best efforts,
business judgment, skill and knowledge to the advancement of the business and
interests of the Company and its Affiliates and to the discharge of his duties
and responsibilities hereunder. The Executive shall not engage in any other
business activity or serve in any industry, trade, professional, governmental or
academic position during the Term of this Agreement, except as may be approved
by the Board of Directors of the Company (the "Board") or its designee.

4 Compensation and Benefits. As compensation for all services performed by the
Executive under and during the term hereof and subject to performance of the
Executive's duties and of the obligations of the Executive to the Company and
its Affiliates, pursuant to this Agreement or otherwise:

(a) Base Salary. During the term hereof, the Company shall pay the Executive a
minimum base salary at the rate of Two Hundred and Sixty-Five Thousand Dollars
($265,000 United States dollars) per annum, payable in accordance with the
payroll practices of the Company for its executives and subject to increase by
the Board, in its sole discretion. Such base salary, as from time to time
increased, is hereafter referred to as the "Base Salary". The Board shall review
the Base Salary no less than annually.

(b) Incentive and Bonus Compensation. During the term hereof, the Executive
shall be entitled to participate in the Company's Executive Incentive Plan, in
accordance with the terms thereof, as such terms may be modified or amended by
the Company from time to time; provided, however, that nothing contained herein
shall obligate the Company to continue such incentive compensation program. The
Executive's target incentive bonus under the Executive Incentive Plan is 40% of
his Base Salary. Such target may be modified by the Company from time to time,
in its sole discretion. Any compensation paid to the Executive under the
Executive Incentive Plan shall be in addition to the Base Salary.

(c) Stock Options. In connection with the commencement of the Executive's
employment, the Executive shall be granted an option to purchase 125,000 shares
of common stock of the Company. At the discretion of the Compensation Committee
of the Board, the Executive may be granted additional options to purchase shares
of stock of the Company in the future. Any existing or future grants, shall be
governed by the terms of the applicable Company stock option plan, as amended
from time to time, and any stock option certificate, stock option agreement, and
other restrictions generally applicable to Company stock options.

(d) Vacations. During the term hereof, the Executive shall be entitled to four
weeks of vacation per annum, to be taken at such times and intervals as shall be
determined by the Executive, subject to the reasonable business needs of the
Company.

(e) Other Benefits. During the term hereof and subject to any contribution
therefore generally required of executives of the Company, the Executive shall
be entitled to participate in any and all employee benefit plans from time to
time in effect for executives of the Company

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generally, except to the extent such plans are in a category of benefit
otherwise provided to the Executive. Such participation shall be subject to (i)
the terms of the applicable plan documents, (ii) generally applicable Company
policies and (iii) the discretion of the Board or any administrative or other
committee provided for in or contemplated by such plan. The Company may alter,
modify, add to or delete its employee benefit plans at any time as it, in its
sole judgment, determines to be appropriate, without recourse by the Executive.

(f) Business Expenses. The Company shall pay or reimburse the Executive for all
reasonable, customary and necessary business expenses incurred or paid by the
Executive in the performance of his/her duties and responsibilities hereunder,
subject to any maximum annual limit and other restrictions on such expenses as
set forth in the Company's Travel Policy as may be amended from time to time,
and to such reasonable substantiation and documentation as may be specified by
the Company from time to time.

5 Termination of Employment and Severance Benefits. Notwithstanding the
provisions of Section 2 hereof, the Executive's employment hereunder shall
terminate prior to the expiration of the term under the following circumstances:

(a) Death. In the event of the Executive's death during the term hereof, the
Executive's employment hereunder shall immediately and automatically terminate.
In the event of the Executive's death during the term hereof, the Company shall
pay to the Executive's designated beneficiary or, if no beneficiary has been
designated by the Executive, to his/her estate, any earned and unpaid Base
Salary and accrued but unused vacation through the date of his/her death.

(b) Disability.

            (i) The Company may terminate the Executive's employment
      hereunder, upon notice to the Executive, in the event that the Executive
      becomes disabled during his/her employment hereunder through any illness,
      injury, accident or condition of either a physical or psychological nature
      and, as a result, is unable to perform substantially all of his/her duties
      and responsibilities hereunder, with or without a reasonable
      accommodation, for ninety (90) days during any period of three hundred and
      sixty-five (365) consecutive calendar days.

            (ii) The Board may designate another employee to act in the
      Executive's place during any period of the Executive's disability.
      Notwithstanding any such designation, the Executive shall continue to
      receive the Base Salary in accordance with Section 4.a and benefits in
      accordance with Section 4.e, to the extent permitted by the then-current
      terms of the applicable benefit plans, until the Executive becomes
      eligible for disability income benefits under the Company's disability
      income plan or until the termination of his/her employment, whichever
      shall first occur.

            (iii) While receiving disability income payments under the
      Company's disability income plan, the Executive shall not be entitled to
      receive any Base Salary under Section 4.a hereof, but shall continue to
      participate in Company benefit plans in accordance with Section 4.e and
      the terms of such plans, until the termination of his/her employment.

            (iv) If any question shall arise as to whether during any
      period the Executive is disabled through any illness, injury, accident or
      condition of either a physical or psychological nature so as to be unable
      to perform substantially all of his/her duties and responsibilities
      hereunder, the Executive may, and at the request of the Company shall,
      submit to a medical examination by a physician selected by the Company to
      whom the Executive or his/her duly appointed guardian, if any, has no
      reasonable objection to determine whether the Executive is so disabled and
      such determination shall for the purposes of this Agreement be conclusive
      of the issue. If such question shall arise and the Executive shall fail to
      submit to such medical examination, the Company's determination of the
      issue shall be binding on the Executive.

            (v) In the event the Company terminates the Executive's
      employment hereunder due to disability, the Company shall pay to the
      Executive any accrued and unpaid Base Salary and accrued but unused
      vacation through the date of termination.

(c) By the Company for Cause. The Company may terminate the Executive's
employment hereunder for Cause at any time upon fourteen (14) day notice to the
Executive setting forth in reasonable detail the nature of such Cause. The
following, as determined by the Company in its reasonable judgment, shall
constitute Cause for termination:

            (i) The Executive's failure to perform (other than by reason
      of disability), or negligence in the performance of, his/her duties and
      responsibilities to the Company or any of its Affiliates; or

            (ii) Material breach by the Executive of any provision of this
      Agreement; or

            (iii) Other conduct by the Executive that is materially
      harmful to the business, interests or reputation of the Company or any of
      its Affiliates.

Upon the giving of notice of termination of the Executive's employment hereunder
for Cause, the Company shall have no further obligation or liability to the
Executive, other than for Base Salary earned and unpaid and accrued vacation
earned but not taken at the date of termination.

(d) By the Company Other than for Cause. The Company may terminate the
Executive's employment hereunder other than for Cause at any time upon notice to
the Executive. In the event of such termination, the Company shall pay the
Executive the higher of (i) benefits payable under an executive severance plan,
if such a plan is in place on the date of termination and if the Executive is
eligible for such benefits under such a plan or (ii) continue to pay the
Executive his Base Salary, at the rate in effect on the date of termination,
until the conclusion of a period of twelve (12) months following the date of
termination. In addition, until the conclusion of a period of twelve (12) months
following the date of termination, the Company shall (A) continue to make
payments to the Executive under the Executive Incentive Plan; and, (B) pay the
full premium cost of the Executive's participation in the Company's group
medical and dental insurance plans, provided that the Executive is entitled

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to continue such participation under applicable law and plan terms. The
payment(s) described in subparagraph (A) shall be equal to the higher of (x) the
Executive's target incentive bonus or (y) the actual incentive bonus paid to the
Executive, if any, under the Executive Incentive Plan for the last full fiscal
year preceding the year in which the Executive's employment is terminated, and
shall be pro-rated for any period less than a full year. The Company will also
provide the Executive with outplacement assistance through a firm of its choice
at a cost not to exceed $15,000. Furthermore, at the sole discretion of the
Compensation Committee of the Board, any unvested options to purchase Company
stock may be accelerated.

(e) By the Executive for Good Reason. The Executive may terminate his/her
employment hereunder for Good Reason, upon notice to the Company setting forth
in reasonable detail the nature of such Good Reason. The following shall
constitute Good Reason for termination by the Executive:

            (i) Failure of the Company to continue the Executive in the
      position of Sr. Vice President of Research and Pre-Clinical Development;
      or

            (ii) Material and substantial diminution in the nature or
      scope of the Executive's responsibilities, duties or authority; however,
      the Company's failure to continue the Executive's appointment or election
      as a director or officer of any of its Affiliates and any diminution of
      the business of the Company or any of its Affiliates, including without
      limitation the sale or transfer of any or all of the assets of the Company
      or any of its Affiliates, shall not constitute "Good Reason"; or

            (iii) Material reduction in Base Salary or benefits due in
accordance with the terms of this Agreement. In the event of termination in
accordance with this Section 5.e, the Company shall pay the Executive the higher
of (i) benefits payable under an executive severance plan, if such a plan is in
place on the date of termination and if the Executive is eligible for such
benefits under such a plan or (ii) continue to pay the Executive his/her Base
Salary, at the rate in effect on the date of termination, until the conclusion
of a period of twelve (12) months following the date of termination. In
addition, until the conclusion of a period of twelve (12) months following the
date of termination, the Company shall (A) continue to make payments to the
Executive under the Executive Incentive Plan; and, (B) pay the full premium cost
of the Executive's participation in the Company's group medical and dental
insurance plans, provided that the Executive is entitled to continue such
participation under applicable law and plan terms. The payment(s) described in
subparagraph (A) above shall be equal to the higher of (x) the Executive's
target incentive bonus or (y) the actual incentive bonus paid to the Executive,
if any, under the Executive Incentive Plan for the last full fiscal year
preceding the year in which the Executive's employment is terminated, and shall
be pro-rated for any period less than a full year. The Company will also provide
the Executive with outplacement assistance through a firm of its choice at a
cost not to exceed $15,000. In addition, at the sole discretion of the
Compensation Committee of the Board, any unvested options to purchase Company
stock may be accelerated.

(f) By the Executive Other than for Good Reason. The Executive may terminate
his/her employment hereunder at any time upon sixty (60) days' notice to the
Company, unless such termination would violate any obligation of the Executive
to the Company under a separate severance agreement. In the event of termination
of the Executive pursuant to this Section 5.f, the Board may elect to waive the
period of notice, or any portion thereof, and, if the Board so elects, the
Company will pay the Executive his/her Base Salary for the notice period (or for
any remaining portion of the period).

(g) Upon a Change of Control.

            (i) If a Change of Control occurs on the date of such Change
      in Control, fifty-percent (50%) of any outstanding unvested stock options
      granted to the Executive as of that date shall become vested and
      exercisable, provided that the Executive is employed by the Company on the
      date of such Change in Control.

            (ii) If a Change of Control occurs and within eighteen (18)
      months following such Change of Control, the Company terminates the
      Executive's employment other than for Cause, or the Executive terminates
      his/her employment for Good Reason, then, in lieu of any payments to or on
      behalf of the Executive under Section 5.d or 5.e hereof, the Company
      shall, until the conclusion of a period of eighteen (18) months following
      the date of termination: (A) continue to pay the Executive the Base Salary
      at the rate in effect on the date of termination; (B) continue to make
      payments to the Executive under the Executive Incentive Plan; and, (C) pay
      the full premium cost of the Executive's participation in the Company's
      group medical and dental insurance plans, provided that the Executive is
      entitled to continue such participation under applicable law and plan
      terms. The payment(s) described in subparagraph (B) above shall be equal
      to the higher of (x) the Executive's target incentive bonus or (y) the
      actual incentive bonus paid to the Executive, if any, under the Executive
      Incentive Plan for the last full fiscal year preceding the year in which
      the Executive's employment is terminated, and shall be pro-rated for any
      period less than a full year. The Executive may at his/her option request
      the Company to make any payments due under (A) or (B) in one-lump sum at
      date of termination. In addition, any outstanding unvested options granted
      to the Executive as of the date of the Change in Control shall become
      vested and shall be exercisable for ninety (90) days following termination
      of the Executive's employment, and the Company will provide the Executive
      with outplacement assistance through a firm of its choice at a cost not to
      exceed $15,000. For the purpose of this Section 5.g alone, in addition to
      the definition provided in Section 5.e, Good Reason shall also mean the
      relocation of the Executive's principal office, without his/her prior
      consent, to a location more than thirty (30) miles from its location on
      the day prior to the Change in Control.

            (iii) All payments required to be made by the Company
      hereunder to Executive or his/her dependents, beneficiaries, or estate
      will be subject to the withholding of such amounts relating to tax and/or
      other payroll deductions as may be required by law.

            In the event that it is determined that any payment or benefit
provided by the Company to or for the benefit of Executive, either under this
Agreement or otherwise, will be subject to the excise tax imposed by Section
4999 of the Internal Revenue Code or any successor provision(s) ("Section
4999"), the Company will, prior to the date on which any amount of the excise
tax must be paid or withheld, make an additional lump-sum payment (the "Gross-up
Payment") to Executive in an amount sufficient, after

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giving effect to all federal, state and other taxes and charges (including
interest and penalties, if any) with respect to the gross-up payment, to make
Executive whole for all taxes (including withholding taxes) and any associated
interest and penalties, imposed under or as a result of Section 4999.

            Determinations under this Section 5.g.iii will be made by an
accounting firm engaged by the Company (the "Firm"). The determinations of the
Firm will be binding upon the Company and Executive except as the determinations
are established in resolution (including by settlement) of a controversy with
the Internal Revenue Service to have been incorrect. All fees and expenses of
the Firm will be paid by the Company.

            If the Internal Revenue Service asserts a claim that, if successful,
would require the Company to make a Gross-up Payment or an additional Gross-up
Payment, the Company and Executive will cooperate fully in resolving the
controversy with the Internal Revenue Service. The Company will make or advance
such Gross-up Payments as are necessary to prevent Executive from having to bear
the cost of payments made to the Internal Revenue Service in the course of, or
as a result of, the controversy. The Firm will determine the amount of such
Gross-up Payments or advances and will determine after final resolution of the
controversy whether any advances must be returned by Executive to the Company.
The Company will bear all expenses of the controversy and will gross Executive
up for any additional taxes that may be imposed upon Executive as a result of
its payment of such expenses.

      (iv) For the purpose of this Section 5.g, a "Change in Control" shall
mean: (A) the acquisition by any Organization of beneficial ownership (within
the meaning of Rule 13d-3 promulgated under the Exchange Act) of 50% or more of
the common stock of the Company; provided, however, that for purposes of the
subsection (A), an acquisition shall not constitute a Change in Control if it
is: (x) by a Benefit Plan sponsored or maintained by the Company or an entity
controlled by the Company or (y) by an entity pursuant to a transaction that
complies with clauses (x), (y) and (z) of subsection (C) of this Section
5(g)(iv); or (B) individuals who, as of May 1, 2004, constitute the Board (the
"Incumbent Board") cease for any reason to constitute at least a majority of the
Board; provided, however, that any individual becoming a director subsequent to
May 1, 2004 whose election, or nomination for election by the Company's
stockholders, was approved by a vote of at least a majority of the directors
then comprising the Incumbent Board (or a majority of the members of a
nominating committee who are members of the Incumbent Board) shall be treated as
a member of the Incumbent Board unless he or she assumed office as a result of
an actual or threatened election contest with respect to the election or removal
of directors or other actual or threatened solicitation of proxies or consents
by or on behalf of an Organization other than the Board; or (C) consummation of
a merger or consolidation involving the Company, or a sale or other disposition
of all or substantially all of the assets of the Company, (a "transaction") in
each case unless, immediately following such transaction, (x) the beneficial
owners of the common stock of the Company outstanding immediately prior to such
transaction beneficially own, directly or indirectly, more than 50% of the
combined voting power of the outstanding voting securities of the entity
resulting from such transaction (including, without limitation, an entity which
as a result of such transaction owns the Company or all or substantially all of
the Company's assets either directly or through one or more subsidiaries), (y)
no Organization (excluding any entity resulting from such transaction or any
Benefit Plan of the Company or such entity resulting from such transaction)
beneficially owns, directly or indirectly, 50% or more of the combined voting
power of the then outstanding voting securities of such entity and (z) at least
a majority of the members of the board of directors or similar board of the
entity resulting from such transaction were members of the Incumbent Board at
the time of the execution of the initial agreement, or of the action of the
Board, providing for such transaction; or (D) approval by the stockholders of
the Company of a complete liquidation or dissolution of the Company. For
purposes of the foregoing: "Benefit Plan" means any employee benefit plan,
including any related trust; "Board" means the Board of Directors of the
Company; "Exchange Act" means the Securities Exchange Act of 1934, as amended;
and "Organization" means any individual, entity or group (within the meaning of
Section 13(d)(3) or Section 14(d)(2) of the Exchange Act).

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(h) Effect of Failure to Renew by Company. In the event the Company chooses not
to renew the term hereof, such failure to renew shall be treated as a
termination by the Company other than for "Cause" unless the Company gives
notice that the failure to renew is for "Cause" as defined in Section 5.c.

6 Effect of Termination. The provisions of this Section 6 shall apply to
termination due to the expiration of the term, termination pursuant to Section 5
or otherwise.

(a) Payment(s) by the Company and contributions to the cost of the Executive's
continued participation in the Company's group health and dental plans that may
be due the Executive in each case under the applicable termination provision of
Section 5 shall constitute the entire obligation of the Company to the
Executive. In order to receive any payments, benefits continuation, accelerated
vesting of stock options or any other benefits under Section 5.d or 5.e or 5.g
or 5.h, the Executive must first execute a General Release of Claims in a form
acceptable to the Company.

(b) Except for medical and dental insurance coverage continued pursuant to
Section 5.d or 5.e or 5.g or 5.h hereof, benefits shall terminate pursuant to
the terms of the applicable benefit plans based on the date of termination of
the Executive's employment without regard to any continuation of Base Salary or
other payment to the Executive following such date of termination.

(c) Provisions of this Agreement shall survive any termination if so provided
herein or if necessary or desirable fully to accomplish the purposes of such
provision, including without limitation the obligations of the Executive under
Sections 7, 8 and 9 hereof. The obligation of the Company to make payments to or
on behalf of the Executive under Section 5.d or 5.e or 5.g or 5.h hereof is
expressly conditioned upon the Executive's continued full performance of
obligations under Sections 7, 8 and 9 hereof. The Executive recognizes that,
except as expressly provided in Section 5.d or 5.e or 5.g or 5.h, no
compensation is earned after termination of employment.

7 Confidential Information.

(a) The Executive acknowledges that the Company and its Affiliates continually
develop Confidential Information, that the Executive may develop Confidential
Information for the Company or its Affiliates and that the Executive may learn
of Confidential Information during the course of employment. The Executive will
comply with the policies and procedures of the Company and its Affiliates for
protecting Confidential Information and shall never disclose to any Person or to
any governmental agency or political subdivision of any government (except as
required by applicable law or for the proper performance of his/her duties and
responsibilities to the Company and its Affiliates), or use for his/her own
benefit or gain, any Confidential Information obtained by the Executive incident
to his/her employment or other association with the Company or any of its
Affiliates. The Executive understands that the restriction shall continue to
apply after his/her employment terminates, regardless of the reason for such
termination.

(b) All documents, records, tapes and other media of every kind and description
relating to the business, present or otherwise, of the Company or its Affiliates
and any copies, in whole or in part, thereof (the "Documents"), whether or not
prepared by the Executive, shall be the sole and exclusive property of the
Company and its Affiliates. The Executive shall safeguard all Documents and
shall surrender to the Company at the time his/her employment terminates, or at
such earlier time or times as the Board or its designee may specify, all
Documents then in the Executive's possession or control.

(c) The Executive acknowledges and agrees that all Confidential Information and
proprietary materials that are provided by the Company to the Executive under
this Agreement are and shall remain the exclusive property of the Company or the
third party entrusting such Confidential Information or proprietary materials to
the Company.

8 Restricted Activities. The Executive agrees that some restrictions on his/her
activities during and after his/her employment are necessary to protect the
goodwill, Confidential Information and other legitimate interests of the Company
and its Affiliates:

(a) While the Executive is employed by the Company and for the greater of (i)
twelve (12) months after his/her employment terminates or (ii) the period during
which the Executive is receiving payments under Section 5.d or 5.e or 5.g or 5.h
(the "Non-Competition Period"), the Executive shall not, directly or indirectly,
whether as owner, partner, investor, consultant, agent, employee, co-venturer or
otherwise, compete with the Company or any of its Affiliates or undertake any
planning for any business competitive with the Company or any of its Affiliates.
Specifically, but without limiting the foregoing, the Executive agrees not to
engage in any manner in any activity that is directly or indirectly competitive
or potentially competitive with the business of the Company or any of its
Affiliates as conducted or under consideration at any time during the
Executive's employment. Restricted activity includes without limitation
accepting employment or a consulting position with any Person who is, or at any
time within twelve (12) months prior to the termination of the Executive's
employment has been, a customer of the Company or any of its Affiliates. For the
purposes of this Section 8, the business of the Company and its Affiliates shall
include all Products and the Executive's undertaking shall encompass all items,
products and services that may be used in substitution for Products. The
foregoing shall not prohibit the Executive's passive ownership of two percent
(2%) or less of the equity securities of any publicly traded company.

(b) The Executive agrees that, during his/her employment with the Company or any
Affiliate of the Company, he/she will not undertake any outside activity,
whether or not competitive with the business of the Company or its Affiliates,
that could reasonably give rise to a conflict of interest or otherwise interfere
with his/her duties and obligations to the Company or any of its Affiliates.

(c) The Executive further agrees that while he/she is employed by the Company or
any Affiliate of the Company and thereafter during the remainder of the
Non-Competition Period, the Executive will not hire or attempt to hire any
employee of the Company or any of its Affiliates, assist in such hiring by any
Person, encourage any such employee to terminate his or her relationship with
the Company or any of its Affiliates or solicit or encourage any customer or
vendor of the Company or any of its Affiliates to terminate its relationship
with them, or, in the case of a customer, to conduct with any Person any
business or activity which such customer conducts or could conduct with the
Company or any of its Affiliates.

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9 Assignment of Rights to Intellectual Property. The Executive shall promptly
and fully disclose, if he/she has not done so already, all Intellectual Property
to the Company. The Executive shall maintain adequate records (whether written,
electronic, or otherwise) to document the Intellectual Property, including
without limitation the conception and reduction to practice of all inventions,
and shall make such records available to the Company upon request. The Company
shall have sole ownership of all Intellectual Property and all such records with
respect thereto. The Executive hereby assigns, conveys, and grants to the
Company (or as otherwise directed by the Company), and agrees to assign, convey
and grant to the Company (or as otherwise directed by the Company), all of
his/her right, title, and interest in and to the Intellectual Property and any
and all patents, patent applications, and copyrights relating to the
Intellectual Property. The Executive agrees to execute any and all applications
for domestic and foreign patents, copyrights or other proprietary rights and to
do such other acts (including without limitation the execution and delivery of
instruments of further assurance or confirmation) requested by the Company to
assign the Intellectual Property to the Company and to permit the Company to
enforce any patents, copyrights or other proprietary rights to the Intellectual
Property. The Executive will not charge the Company for time spent in complying
with these obligations. All copyrightable works that the Executive creates shall
be considered "work made for hire".

The Executive represents that the attached Exhibit A contains a complete list of
all inventions, copyrightable works, tangible materials, and other intellectual
property that the Executive (either alone or jointly with others) conceived,
developed, discovered, created, or reduced to practice prior to the Effective
Date (the "Prior IP"). The Prior IP is not assigned to the Company under this
Agreement, except to the extent that the Executive expressly assigns such Prior
IP to the Company under the terms of a separate written instrument. If no Prior
IP is listed on Exhibit A, the Executive represents that no Prior IP exists. The
Executive recognizes that the protection of the Intellectual Property of the
Company against unauthorized disclosure and use is of critical importance to the
Company, and therefore, the Executive agrees to use his/her best efforts and
exercise utmost diligence to protect and safeguard the Intellectual Property of
the Company and its Affiliates, if any, and, except as may be expressly required
by the Company in connection with the Executive's performance of his/her
obligations to the Company under this Agreement, the Executive shall not, either
during the term of this Agreement or thereafter, directly or indirectly, use for
his/her own benefit or for the benefit of another, or disclose to another, any
of such Intellectual Property.

10 Notification Requirement. Until the conclusion of the Non-Competition Period
the Executive shall give notice to the Company of each new business activity
he/she plans to undertake, at least twenty-one (21) days prior to beginning any
such activity. Such notice shall state the name and address of the Person for
whom such activity is undertaken and the nature of the Executive's business
relationship(s) and position(s) with such Person. The Executive shall provide
the Company with such other pertinent information concerning such business
activity as the Company may reasonably request in order to determine the
Executive's continued compliance with his/her obligations under Sections 7, 8
and 9 hereof.

11 Enforcement of Covenants. The Executive acknowledges that he/she has
carefully read and considered all the terms and conditions of this Agreement,
including the restraints imposed upon him pursuant to Sections 7 and 8 hereof.
The Executive agrees that said restraints are necessary for the reasonable and
proper protection of the Company and its Affiliates and that each and every one
of the restraints is reasonable in respect to subject matter, length of time and
geographic area. The Executive further acknowledges that, were he/she to breach
any of the covenants contained in Sections 7 or 8 hereof, the damage to the
Company would be irreparable. The Executive therefore agrees that the Company,
in addition to any other remedies available to it, shall be entitled to
preliminary and permanent injunctive relief against any breach or threatened
breach by the Executive of any of said covenants, without having to post bond.
The parties further agree that, in the event that any provision of Section 7 or
8 hereof shall be determined by any court of competent jurisdiction to be
unenforceable by reason of its being extended over too great a time, too large a
geographic area or too great a range of activities, such provision shall be
deemed to be modified to permit its enforcement to the maximum extent permitted
by law.

12 Conflicting Agreements. The Executive hereby represents and warrants that the
execution of this Agreement and the performance of his/her obligations hereunder
will not breach or be in conflict with any other agreement to which the
Executive is a party or is bound and that the Executive is not now subject to
any covenants against competition or similar covenants that would affect the
performance of his/her obligations hereunder. The Executive will not disclose to
or use on behalf of the Company any proprietary information of a third party
without such party's consent.

13 Indemnification. The Company shall indemnify the Executive to the extent
provided in its then current Articles or By-Laws. The Executive agrees to
promptly notify the Company of any actual or threatened claim arising out of or
as a result of his/her employment with the Company.

14 Definitions. Words or phrases which are initially capitalized or are within
quotation marks shall have the meanings provided in this Section 14 and as
provided elsewhere herein. For purposes of this Agreement, the following
definitions apply:

(a) "Affiliates" means all persons and entities directly or indirectly
controlling, controlled by or under common control with the Company, where
control may be by either management authority or equity interest.

(b) "Confidential Information" means any and all information of the Company and
its Affiliates that is not generally known by others. Confidential Information
includes without limitation such information relating to (i) the development,
research, testing, manufacturing, marketing and financial activities of the
Company and its Affiliates, (ii) the Products, (iii) the costs, sources of
supply, financial performance and strategic plans of the Company and its
Affiliates, (iv) the identity and special needs of the customers of the Company
and its Affiliates and (v) the people and organizations with whom the Company
and its Affiliates have business relationships and those relationships.
Confidential Information also includes comparable information that the Company
or any of its Affiliates have received belonging to others or which was received
by the Company or any of its Affiliates with any understanding that it would not
be disclosed.

(c) "Intellectual Property" means inventions, discoveries, developments,
methods, processes, compositions, works, concepts and ideas (whether or not
patentable or copyrightable or constituting trade secrets) conceived, made,
created, developed or reduced to practice by the Executive (whether alone or
with others, whether or not during normal business hours or on or off Company
premises) during the Executive's employment and during the period of twelve (12)
months immediately following termination of his/her employment that relate to
either the

<PAGE>

Products or any prospective activity of the Company or any of its Affiliates.

(d) "Person" means an individual, a corporation, an association, a partnership,
an estate, a trust and any other entity or organization, other than the Company
or any of its Affiliates.

(e) "Products" mean all products planned, researched, developed, under
development, tested, manufactured, sold, licensed, leased or otherwise
distributed or put into use by the Company or any of its Affiliates, together
with all services provided or planned by the Company or any of its Affiliates,
during the Executive's employment.

15 Withholding. All payments made by the Company under this Agreement shall be
reduced by any tax or other amounts required to be withheld by the Company under
applicable law.

16 Assignment. Neither the Company nor the Executive may make any assignment of
this Agreement or any interest herein, by operation of law or otherwise, without
the prior written consent of the other; provided, however, that the Company may
assign its rights and obligations under this Agreement without the consent of
the Executive in the event that the Company shall hereafter affect a
reorganization, consolidate with, or merge into, any other Person or transfer
all or substantially all of its properties or assets to any other Person. This
Agreement shall inure to the benefit of and be binding upon the Company and the
Executive, their respective successors, executors, administrators, heirs and
permitted assigns.

17 Severability. If any portion or provision of this Agreement shall to any
extent be declared illegal or unenforceable by a court of competent
jurisdiction, then the remainder of this Agreement, or the application of such
portion or provision in circumstances other than those as to which it is so
declared illegal or unenforceable, shall not be affected thereby, and each
portion and provision of this Agreement shall be valid and enforceable to the
fullest extent permitted by law.

18 Waiver. No waiver of any provision hereof shall be effective unless made in
writing and signed by the waiving party. The failure of either party to require
the performance of any term or obligation of this Agreement, or the waiver by
either party of any breach of this Agreement, shall not prevent any subsequent
enforcement of such term or obligation or be deemed a waiver of any subsequent
breach.

19 Notices. Any and all notices, requests, demands and other communications
provided for by this Agreement shall be in writing and shall be effective when
delivered in person or deposited in the United States mail, postage prepaid,
registered or certified, and addressed to the Executive at his/her last known
personal address on the books of the Company or, in the case of the Company, at
its principal place of business, attention of Associate General Counsel, or to
such other address as either party may specify by notice to the other actually
received.

20 Entire Agreement. This Agreement constitutes the entire agreement between the
parties and supersedes all prior communications, agreements and understandings,
written or oral, with respect to the terms and conditions of the Executive's
employment, excluding any obligations with respect to the securities of the
Company or the grant of any stock options.

21 Amendment. This Agreement may be amended or modified only by a written
instrument signed by the Executive and by an expressly authorized representative
of the Company.

22 Headings. The headings and captions in this Agreement are for convenience
only and in no way define or describe the scope or content of any provision of
this Agreement.

23 Counterparts. This Agreement may be executed in two or more counterparts,
each of which shall be an original and all of which together shall constitute
one and the same instrument.

24 Governing Law. This is a contract and shall be construed and enforced under
and be governed in all respects by the laws of the Commonwealth of
Massachusetts, without regard to the conflict of laws principles thereof.

                            [SIGNATURE PAGE FOLLOWS]

<PAGE>

IN WITNESS WHEREOF, this Agreement has been executed as a sealed instrument by
the Company, by its duly authorized representative, and by the Executive, as of
the date first above written.

THE EXECUTIVE:                       ANTIGENICS INC.

/s/ Roman Chicz                      By: /s/ Garo H. Armen
------------------------                 --------------------------

                                     Title: Chairman and CEO

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                                    EXHIBIT A

          LIST OF PRIOR INTELLECTUAL PROPERTY