Exhibit 10.1

Confidential

AMENDMENT – NUMBER ONE

AGREEMENT

This Amendment Number One (this “Amendment 1”) is effective as of July 2, 2009
by and between Antigenics Inc., a Delaware corporation, having its principle
place of business at 3 Forbes Road, Lexington, Massachusetts 02421, USA (the
“Company”) and Garo Armen (the “Executive”). Capitalized terms not otherwise
defined herein shall have the meaning set forth in the Agreement (defined
below).

WITNESSETH

WHEREAS, the parties have entered into an Agreement effective as December 1,
2005 setting forth employment terms (the “Agreement”); and

WHEREAS, the parties now wish to amend the Agreement to reflect certain changes
in the Company’s Executive Change in Control Plan as set forth herein;

NOW, THEREFORE, the parties agree as follows:

 

  1. Section 5(g)(i) of the Agreement is hereby deleted in its entirety and
replaced with the following:

(i) if a Change of Control occurs on the date of such Change in Control,
fifty-percent (50%) of any (A) outstanding unvested stock options or (B) shares
of unvested restricted stock of the Company, granted or issued to the Executive
as of the date of the Change in Control shall become vested, exercisable and, in
the case of shares of restricted stock, no longer subject to forfeiture,
provided that the Executive is employed by the Company on the date of such
Change in Control.

 

  2. Section 5(g)(ii) of the Agreement is hereby deleted in its entirety and
replaced with the following:

(ii) if a Change of Control occurs and within twenty-four (24) 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) twenty-four (24) months Base Salary at the rate in effect on the
date of termination. plus (B) two times 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 twenty-four

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(24) 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 (I) outstanding unvested
stock options granted or issued 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 (II) shares of unvested
restricted stock of the Company granted or issued to the Executive as of the
date of the Change in Control shall become vested and no longer subject to
forfeiture. 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. 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 in Control.

 

  3. Section 6(a) of the Agreement is hereby deleted in its entirety and
replaced with the following:

(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 shares of restricted stock 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.

 

  4. The parties acknowledge and agree that, except as set forth in this
Amendment 1, the Agreement shall remain in full force and effect.

 

  5. This Amendment 1 shall be governed by and construed in accordance with the
laws of the Commonwealth of Massachusetts, U.S.A. irrespective of any conflicts
of law principles thereof.

 

  6. This Amendment 1 may be executed by the parties hereto in separate
counterparts, each of which when so executed and delivered shall be an original,
but all such counterparts shall together constitute one and the same instrument.
Each counterpart may consist of a number of copies hereof each signed by less
than all, but together signed by all of the parties hereto.

[SIGNATURE PAGE FOLLOWS]

 

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Confidential

IN WITNESS WHEREOF, the parties each have caused this Amendment 1 to be executed
by their respective duly authorized representative as of the date first set
forth above.

 

ANTIGENICS INC., a Delaware corporation

By:

 

/s/ Wadih Jordan

Name:

  Wadih Jordan

Title:

  Director

Executive

By:

 

/s/ Garo Armen

Name:

  Garo Armen

 

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