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                                                                    EXHIBIT 10.3

                                 FIRST AMENDMENT

     FIRST AMENDMENT TO THE 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 "Agreement").

     WHEREAS, the Company and the Executive entered into the Agreement to
establish the terms and conditions of the Executive's employment with the
Company; and

     WHEREAS, the Company and the Executive now wish to amend the Agreement to
modify certain material terms of their agreement to preserve their intent while
reducing the risk of such terms causing the Executive to be required to include
amounts in income under Section 409A of the Internal Revenue Code;

     NOW, THEREFORE, in consideration of the foregoing premises and other good
and valuable consideration, the parties hereby amend the Agreement, effective as
of the 1st day of December 2005 (the "Effective Date") as follows:

     1. The first sentence of Section 5 is amended by inserting after the comma
the words "but subject to Section 6 hereof" followed by a comma.

     2. Section 5.d is amended to read in its entirety as follows:

     "(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 either (i)
pay the Executive the 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, if the present value to the
Executive is greater, (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, the Company
shall pay to the Executive in one lump sum an amount equal to the higher of (x)
the Executive's target incentive bonus under the Executive Incentive Plan for
the year in which the Executive's employment is terminated 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 also, until the conclusion of a period of
twelve (12) months following the date of termination, 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 Company will also provide
the Executive with an outplacement assistance benefit in the form of a lump-sum
payment of $15,000 plus an additional lump-sum payment in an amount sufficient,
after giving effect to all federal, state and other taxes with respect to such
additional payment, to make Executive whole for all taxes (including withholding
taxes) on such outplacement assistance benefit. Furthermore, at the sole

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discretion of the Compensation Committee of the Board, any unvested options to
purchase Company stock may be accelerated."

     3. Section 5.e is amended by deleting the flush language following
subparagraph (iii) and inserting in lieu thereof the following:

"In the event of termination in accordance with this Section 5.e, the Company
shall either (i) pay the Executive the 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, if the present
value to the Executive is greater, (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, the Company shall pay to the Executive in one lump sum an amount equal
to the higher of (x) the Executive's target incentive bonus under the Executive
Incentive Plan for the year in which the Executive's employment is terminated 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 also, until the
conclusion of a period of twelve (12) months following the date of termination,
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
Company will also provide the Executive with an outplacement assistance benefit
in the form of a lump-sum payment of $15,000 plus an additional lump-sum payment
in an amount sufficient, after giving effect to all federal, state and other
taxes with respect to such additional payment, to make Executive whole for all
taxes (including withholding taxes) on such outplacement assistance benefit. In
addition, at the sole discretion of the Compensation Committee of the Board, any
unvested options to purchase Company stock may be accelerated."

     4. Subparagraph (ii) of Section 5.g is amended to read in its entirety as
follows:

          "(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 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 pay to the Executive in one
lump sum an amount equal to (A) eighteen (18) months Base Salary at the rate in
effect on the date of termination, plus (B) 150% of the higher of (x) the
Executive's target incentive bonus under the Executive Incentive Plan for the
year in which the Executive's employment is terminated 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 also, until the conclusion of a period of
eighteen (18) months following the date of termination, 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. 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. The Company will also
provide the Executive with an outplacement assistance benefit in the form of a
lump-sum payment of $15,000 plus an additional lump-sum payment in an amount
sufficient, after giving effect to all federal, state and


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other taxes with respect to such additional payment, to make Executive whole for
all taxes (including withholding taxes) on such outplacement assistance benefit.
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 prior consent, to a location more than
thirty (30) miles from its location on the day prior to the Change of Control."

     5. Section 6 is amended by adding the following paragraphs (d) and (e)
immediately after paragraph (c) thereof:

          "(d) Any lump-sum payments to be made to the Executive hereunder shall
be made as soon as administratively practicable and in any event no later than 2
1/2 months after the end of the year in which the Executive becomes entitled to
such payment.

          (e) To the extent any payment hereunder shall be required to be
delayed until six months following separation from service to comply with the
"specified employee" rules of Section 409A of the Internal Revenue Code, it
shall be delayed (but not more than is required) to comply with such rules, and
shall promptly after such delay be paid with interest at a reasonable market
rate as determined by the Company."

          The first sentence of Section 6(c) is amended and restated as follows:

          "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, 9 and 13 hereof."

     IN WITNESS WHEREOF, this First Amendment has been executed as a sealed
instrument by the Company, by its duly authorized representative, and by the
Executive, as of the Effective Date set forth herein.

THE EXECUTIVE:                          ANTIGENICS, INC.


/s/ Roman Chicz                         By: /s/ Garo H. Armen
-------------------------------------       ------------------------------------
                                        Title: Chairman & CEO


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