content: <PAGE>   1
     As filed with the Securities and Exchange Commission on September 18, 2001
  
                                REGISTRATION NO. 333-
  
                         SECURITIES AND EXCHANGE COMMISSION
                               WASHINGTON, D.C. 20549
  
                                      FORM S-8
                            REGISTRATION STATEMENT UNDER
                             THE SECURITIES ACT OF 1933
  
                                   ANTIGENICS INC.
               (Exact Name of Registrant as Specified in its Charter)
  
  
             DELAWARE                                    06-1562417
    (State or Other Jurisdiction            (I.R.S. Employer Identification No.)
         of Incorporation)
  
               630 FIFTH AVENUE, SUITE 2100, NEW YORK, NEW YORK 10111
                      (Address of Principal Executive Offices)
  
      ARONEX PHARMACEUTICALS, INC. AMENDED AND RESTATED 1989 STOCK OPTION PLAN
                  ARONEX PHARMACEUTICALS, INC. AMENDED AND RESTATED
                    1993 NON-EMPLOYEE DIRECTOR STOCK OPTION PLAN
      ARONEX PHARMACEUTICALS, INC. AMENDED AND RESTATED 1998 STOCK OPTION PLAN
                           (AS ASSUMED BY ANTIGENICS INC.)
                              (Full Title of the Plan)
  
                                GARO H. ARMEN, PH.D.
                               Chief Executive Officer
                                   Antigenics Inc.
                            630 Fifth Avenue, Suite 2100
                              New York, New York 10111
                                   (212) 332-4774
              (Name, Address and Telephone Number of Agent for Service)
  
  
                                   with copies to:
                               PAUL M. KINSELLA, ESQ.
                                 Palmer & Dodge LLP
                                  One Beacon Street
                             Boston, Massachusetts 02108
                                   (617) 573-0100
  
                           CALCULATION OF REGISTRATION FEE
  
  <TABLE>
  <CAPTION>
                                                                                 PROPOSED MAXIMUM    PROPOSED MAXIMUM      AMOUNT OF
                                                              AMOUNT TO BE        OFFERING PRICE        AGGREGATE        REGISTRATION
    TITLE OF EACH CLASS OF SECURITIES TO BE REGISTERED        REGISTERED(1)         PER SHARE       OFFERING PRICE(2)         FEE
    --------------------------------------------------        -------------      ----------------   -----------------    ------------
  <S>                                                         <C>                <C>                <C>                  <C>
  Aronex Pharmaceuticals, Inc. Amended and Restated 1989
  Stock Option Plan:
           Common Stock, $0.01 par value                      56,574 shares           $76.48            $4,326,780         $1,081.70
  
  Aronex Pharmaceuticals, Inc. Amended and Restated 1993
  Non-employee Director Stock Option Plan:
           Common Stock, $0.01 par value                      34,731 shares           $75.66            $2,627,747         $  656.94
  
  Aronex Pharmaceuticals, Inc. Amended and Restated 1998
  Stock Option Plan:
           Common Stock, $0.01 par value                      81,006 shares           $32.19            $2,607,583         $  651.90
                                                                                                                           =========
  Total                                                      172,311 shares                                                $2,390.54
  </TABLE>
  
  (1)  Pursuant to Rule 416 under the Securities Act of 1933, to the extent
       additional shares of our common stock may be issued or issuable as a result
       of a stock split or other distribution declared at any time by the Board of
       Directors while this registration statement is in effect, this registration
       statement is hereby deemed to cover all such additional shares of common
       stock.
  
  (2)  Estimated solely for the purpose of determining the registration fee and
       computed pursuant to Rule 457(h)(1). The proposed maximum aggregate
       offering price indicated is based on the weighted average price per share
       in effect for the outstanding options under the Aronex Pharmaceuticals,
       Inc. Amended and Restated 1989 Stock Option Plan ($76.48), the Aronex
       Pharmaceuticals, Inc. Amended and Restated 1993 Non-Employee Director Stock
       Option Plan ($75.66) and the Aronex Pharmaceuticals, Inc. 1998 Stock Option
       Plan ($32.19), as assumed by Antigenics Inc.
  <PAGE>   2
                                       PART II
  
                 INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.
  
  The following documents previously filed with the Securities and Exchange
  Commission are incorporated by reference herein and shall be deemed as part
  hereof:
  
              (a)   our Annual Report on Form 10-K for the fiscal year ended
                    December 31, 2000, filed with the SEC on March 28, 2001;
  
              (b)   all of our other reports filed pursuant to Section 13(a) or
                    15(d) of the Securities Exchange Act of 1934, as amended (the
                    "Exchange Act"), since December 31, 2000; and
  
              (c)   the description of our common stock contained in our
                    Registration Statement on Form 8-A filed on January 24, 2000,
                    including any amendment or report filed hereafter for the
                    purpose of updating such description.
  
  All documents filed after the date of this registration statement pursuant to
  Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act and prior to the filing
  of a post-effective amendment that indicates that all shares of common stock
  offered hereunder have been sold or that deregisters all shares of common stock
  remaining unsold shall be deemed to be incorporated by reference herein and to
  be a part hereof from the date of the filing of such reports and documents. Any
  statement contained in a document incorporated or deemed to be incorporated by
  reference herein shall be deemed to be modified or superseded for purposes of
  this registration statement to the extent that a statement contained herein or
  in any other subsequently filed document that also is or is deemed to be
  incorporated by reference herein modifies or supersedes such statement. Any
  statement so modified or superseded shall not be deemed, except as so modified
  or superseded, to constitute as part of this registration statement.
  
  ITEM 4.  DESCRIPTION OF SECURITIES.
  
  Not applicable.
  
  ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.
  
  Not applicable.
  
  ITEM 6.  INDEMNIFICATION OF OFFICERS AND DIRECTORS.
  
  Section 145 of the Delaware General Corporation Law provides that a corporation
  may indemnify any person who was or is a party or is threatened to be made a
  party to any threatened, pending or completed action, suit or proceeding,
  whether civil, criminal, administrative or investigative, other than an action
  by or in the right of the corporation, by reason of the fact that the person is
  or was a director, officer, employee or agent of the corporation or is or was
  serving at the corporation's request as a director, officer, employee or agent
  of another corporation, partnership, joint venture, trust or other enterprise,
  against expenses, including attorneys' fees, judgments, fines and amounts paid
  in settlement actually and reasonably incurred by the person in connection with
  the action, suit or proceeding if the person acted in good faith and in a manner
  the person reasonably believed to be in or not opposed to the best interests of
  the corporation, and, with respect to any criminal action or proceeding, had no
  reasonable cause to believe the person's conduct was unlawful. The power to
  indemnify applies to actions brought by or in the right of
  
  
                                        II-1
  <PAGE>   3
  the corporation as well, but only to the extent of expenses, including
  attorneys' fees but excluding judgments, fines and amounts paid in settlement,
  actually and reasonably incurred by the person in connection with the defense or
  settlement of the action or suit. In these actions no indemnification shall be
  made in the event of any adjudication of negligence or misconduct in the
  performance of his duties to the corporation, unless a court believes that in
  light of all the circumstances indemnification should apply.
  
  Article V of Antigenics' By-laws provides that Antigenics shall, to the extent
  legally permitted, indemnify each person who was or is a party or is threatened
  to be made a party to any threatened, pending or completed action, suit or
  proceeding by reason of the fact that he is or was, or has agreed to become, a
  director or officer of Antigenics, or is or was serving, or has agreed to serve,
  at the request of Antigenics, as a director, officer or trustee of, or in a
  similar capacity with, another corporation, partnership, joint venture, trust or
  other enterprises. The indemnification provided for in Article V is expressly
  not exclusive of any other rights to which those seeking indemnification may be
  entitled under any law, agreement or vote of stockholders or disinterested
  directors or otherwise, and shall inure to the benefit of the heirs, executors
  and administrators of such persons.
  
  Section 145(g) of the Delaware General Corporation Law and Article V of By-laws
  of Antigenics provide that the company shall have the power to purchase and
  maintain insurance on behalf of its officers, directors, employees and agents,
  against any liability asserted against and incurred by such persons in any such
  capacity.
  
  Antigenics has entered into indemnification agreements with each of its
  directors and executive officers and has obtained insurance covering its
  directors and officers against losses and insuring Antigenics against certain of
  its obligations to indemnify its directors and officers.
  
  Section 102(b)(7) of the General Corporation Law of the State of Delaware
  provides that a corporation may eliminate or limit the personal liability of a
  director to the corporation or its stockholders for monetary damages for breach
  of fiduciary duty as a director, provided that such provisions shall not
  eliminate or limit the liability of a director (i) for any breach of the
  director's duty of loyalty to the corporation or its stockholders, (ii) for acts
  or omissions not in good faith or which involve intentional misconduct or a
  knowing violation of law, (iii) under Section 174 of the General Corporation Law
  of the State of Delaware, or (iv) for any transaction from which the director
  derived an improper personal benefit. No such provision shall eliminate or limit
  the liability of a director for any act or omission occurring prior to the date
  when such provision becomes effective.
  
  Pursuant to the Delaware General Corporation Law, Section 6 of Article FIFTH of
  the Certificate of Incorporation of Antigenics eliminates a director's personal
  liability for monetary damages to Antigenics and its stockholders for breach of
  fiduciary duty as a director, except in circumstances involving a breach of the
  director's duty of loyalty to Antigenics or its stockholders, acts or omissions
  not in good faith, intentional misconduct, knowing violations of the law,
  self-dealing or the unlawful payment of dividends or repurchase of stock.
  
  ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.
  
  Not applicable.
  
  
                                        II-2
  <PAGE>   4
  ITEM 8.  EXHIBITS.
  
  <TABLE>
  <CAPTION>
      EXHIBIT      DESCRIPTION
      -------      -----------
      NUMBER
      ------
  <S>              <C>
        4.1        Certificate of Incorporation of Antigenics Inc. Filed as Exhibit 3.1 to our Registration Statement
                   on Form S-1 (File No. 333-91747) and incorporated herein by reference.
  
        4.2        By-laws of Antigenics Inc. Filed as Exhibit 3.2 to our Registration Statement on Form S-1 (File No.
                   333-91747) and incorporated herein by reference.
  
        4.3        Form of Warrant to purchase Common Stock, together with a list of holders. Filed as Exhibit 4.1 to
                   our Registration Statement on Form S-1 (File No. 333-91747) and incorporated herein by reference.
  
        4.4        Form of Subscription Agreement, as amended, together with a list of parties thereto. Filed as
                   Exhibit 4.2 to our Registration Statement on Form S-1 (File No. 333-91747) and incorporated herein
                   by reference.
  
        5.1        Opinion of Palmer & Dodge LLP.  Filed herewith.
  
       23.1        Consent of KPMG LLP.  Filed herewith.
  
       23.2        Consent of PricewaterhouseCoopers LLP.  Filed herewith.
  
       23.3        Consent of Arthur Andersen LLP.  Filed herewith.
  
       23.4        Consent of Palmer & Dodge LLP. Included in the opinion filed as Exhibit 5.1.
  
       24.1        Power of Attorney.  Included on the signature page hereto.
  </TABLE>
  
  ITEM 9.  UNDERTAKINGS.
  
              (a)   The undersigned registrant hereby undertakes:
  
                    (1)   To file, during any period in which offers or sales are
                          being made, a post-effective amendment to this
                          registration statement:
  
                          (i)   To include any prospectus required by Section 10
                                (a)(3) of the Securities Act of 1933;
  
                          (ii)  To reflect in the prospectus any facts or events
                                arising after the effective date of this
                                registration statement (or the most recent
                                post-effective amendment thereof) which,
                                individually or in the aggregate, represents a
                                fundamental change in the information set forth in
                                this registration statement;
  
                          (iii) To include any material information with respect
                                to the plan of distribution not previously
                                disclosed in this registration statement or any
                                material change to such information in this
                                registration statement;
  
                                provided, however, that paragraphs (a) (1) (i) and
                                (a) (1) (ii) do not apply if the information
                                required to be included in a post-effective
                                amendment by
  
  
                                        II-3
  <PAGE>   5
                                those paragraphs is contained in periodic reports
                                filed with or furnished to the Commission by the
                                registrant pursuant to Section 13 or Section 15(d)
                                of the Exchange Act of 1934 that are incorporated
                                by reference in this registration statement.
  
                    (2)   That, for the purpose of determining any liability under
                          the Securities Act of 1933, each such post-effective
                          amendment shall be deemed to be a new registration
                          statement relating to the securities offered therein,
                          and the offering of such securities at that time shall
                          be deemed to be the initial bona fide offering thereof.
  
                    (3)   To remove from registration by means of a post-effective
                          amendment any of the securities being registered which
                          remain unsold at the termination of the offering.
  
              (b)   The undersigned registrant hereby undertakes that, for
                    purposes of determining any liability under the Securities Act
                    of 1933, each filing of the registrant's annual report
                    pursuant to Section 13(a) or Section 15(d) of the Exchange Act
                    of 1934 that is incorporated by reference in this registration
                    statement shall be deemed to be a new registration statement
                    relating to the securities offered therein and the offering of
                    such securities at that time shall be deemed to be initial
                    bona fide offering thereof.
  
              (c)   Insofar as indemnification for liabilities arising under the
                    Securities Act of 1933 may be permitted to directors, officers
                    and controlling persons of the registrant pursuant to the
                    provisions referred to in Item 6 hereof, or otherwise, the
                    registrant has been advised that in the opinion of the
                    Securities and Exchange Commission such indemnification is
                    against public policy as expressed in the Securities Act of
                    1933 and is, therefore, unenforceable. In the event that a
                    claim for indemnification against such liabilities (other than
                    the payment by the registrant of expenses incurred or paid by
                    a director, officer or controlling person of the registrant in
                    the successful defense of any action, suit or proceeding) is
                    asserted by such director, officer, or controlling person in
                    connection with the securities being registered, the
                    registrant will, unless in the opinion of its counsel the
                    matter has been settled by controlling precedent, submit to a
                    court of appropriate jurisdiction the question whether such
                    indemnification by it is against public policy as expressed in
                    the Securities Act of 1933 and will be governed by the final
                    jurisdiction of such issue.
  
  
                                        II-4
  <PAGE>   6
                                     SIGNATURES
  
  Pursuant to the requirements of the Securities Act of 1933, the registrant
  certifies that it has reasonable grounds to believe that it meets all of the
  requirements for filing on Form S-8 and has duly caused this Registration
  Statement to be signed on its behalf by the undersigned, thereunto duly
  authorized, in the Town of Woburn, Commonwealth of Massachusetts, as of
  September 18, 2001.
  
                                      ANTIGENICS INC.
  
                                      By:   /s/ Garo H. Armen, Ph.D.
                                      --------------------------------------------
                                            Garo H. Armen, Ph.D.
                                            Chief Executive Officer and
                                            Chairman of the Board of Directors
  
                                  POWER OF ATTORNEY
  
  We, the undersigned officers and directors of Antigenics Inc., hereby severally
  constitute and appoint Garo H. Armen, Ph.D. and Paul M. Kinsella and each of
  them singly, our true and lawful attorneys-in-fact, with full power to them in
  any and all capacities, to sign any and all amendments to this Registration
  Statement on Form S-8 (including any post-effective amendments thereto), and to
  file the same, with exhibits thereto and other documents in connection
  therewith, with the Securities and Exchange Commission, hereby ratifying and
  confirming all that each of said attorneys-in-fact may do or cause to be done by
  virtue hereof.
  
  Pursuant to the requirements of the Securities Act of 1933, this registration
  statement has been signed below by the following persons in the capacities and
  as of the dates indicated.
  
  <TABLE>
  <CAPTION>
  Signature                                   Title                                       Date
  ---------                                   -----                                       ----
  <S>                                         <C>                                         <C>
  /s/ Garo H. Armen, Ph.D.                    Chief Executive Officer and                 September 18, 2001
  ----------------------------------          Chairman of the Board of Directors
  Garo H. Armen, Ph.D.                        (Principal Executive Officer and
                                              Principal Financial and Accounting
                                              Officer)
  
  /s/ Pramod Srivastava, Ph.D.                Director                                    September 18, 2001
  ----------------------------------
  Pramod Srivastava, Ph.D.
  
  
  /s/ Noubar Afeyan, Ph.D.                    Director                                    September 18, 2001
  ----------------------------------
  Noubar Afeyan, Ph.D.
  
  
  /s/ Gamil de Chadarevian                    Vice Chairman of the Board                  September 18, 2001
  ----------------------------------          of Directors
  Gamil de Chadarevian
  
  
  /s/ Tom Dechaene                            Director                                    September 18, 2001
  ----------------------------------
  Tom Dechaene
  
  
  /s/ Martin Taylor                           Director                                    September 18, 2001
  ----------------------------------
  Martin Taylor
  
  
  /s/ Sanford M. Litvack                      Director                                    September 18, 2001
  ----------------------------------
  Sanford M. Litvack
  
  
                                              Director
  ----------------------------------
  Samuel Waksal, Ph.D.
  
  </TABLE>
  
  
                                        II-5
  <PAGE>   7
                                    EXHIBIT INDEX
  
  <TABLE>
  <CAPTION>
      EXHIBIT      DESCRIPTION
      -------      -----------
      NUMBER
      ------
  <S>              <C>
        4.1        Certificate of Incorporation of Antigenics Inc. Filed as Exhibit 3.1 to our Registration
                   Statement on Form S-1 (File No. 333-91747) and incorporated herein by reference.
  
        4.2        By-laws of Antigenics Inc. Filed as Exhibit 3.2 to our Registration Statement on Form S-1 (File
                   No. 333-91747) and incorporated herein by reference.
  
        4.3        Form of Warrant to purchase Common Stock, together with a list of holders. Filed as Exhibit 4.1
                   to our Registration Statement on Form S-1 (File No. 333-91747) and incorporated herein by
                   reference.
  
        4.4        Form of Subscription Agreement, as amended, together with a list of parties thereto. Filed as
                   Exhibit 4.2 to our Registration Statement on Form S-1 (File No. 333-91747) and incorporated
                   herein by reference.
  
        5.1        Opinion of Palmer & Dodge LLP.  Filed herewith.
  
       23.1        Consent of KPMG LLP.  Filed herewith.
  
       23.2        Consent of PricewaterhouseCoopers LLP.  Filed herewith.
  
       23.3        Consent of Arthur Andersen LLP.  Filed herewith.
  
       23.4        Consent of Palmer & Dodge LLP. Included in the opinion filed as Exhibit 5.1.
  
       24.1        Power of Attorney.  Included on the signature page hereto.
  </TABLE>
  
  
                                        II-6
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metadata_filer: {"company-data": {"conformed-name": "ANTIGENICS INC /DE/", "cik": "0001098972", "assigned-sic": "2836", "irs-number": "061562417", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-69580", "film-number": "1739872"}, "business-address": {"street1": "630 FIFTH AVENUE SUITE 2170", "city": "NEW YORK", "state": "NY", "zip": "10111", "phone": "2123324774"}, "mail-address": {"street1": "630 FIFTH AVENUE SUITE 2170", "city": "NEW YORK", "state": "NY", "zip": "10111"}}
text: 1
     As filed with the Securities and Exchange Commission on September 18, 2001
  
                                REGISTRATION NO. 333-
  
                         SECURITIES AND EXCHANGE COMMISSION
                               WASHINGTON, D.C. 20549
  
                                      FORM S-8
                            REGISTRATION STATEMENT UNDER
                             THE SECURITIES ACT OF 1933
  
                                   ANTIGENICS INC.
               (Exact Name of Registrant as Specified in its Charter)
  
             DELAWARE                                    06-1562417
    (State or Other Jurisdiction            (I.R.S. Employer Identification No.)
         of Incorporation)
  
               630 FIFTH AVENUE, SUITE 2100, NEW YORK, NEW YORK 10111
                      (Address of Principal Executive Offices)
  
      ARONEX PHARMACEUTICALS, INC. AMENDED AND RESTATED 1989 STOCK OPTION PLAN
                  ARONEX PHARMACEUTICALS, INC. AMENDED AND RESTATED
                    1993 NON-EMPLOYEE DIRECTOR STOCK OPTION PLAN
      ARONEX PHARMACEUTICALS, INC. AMENDED AND RESTATED 1998 STOCK OPTION PLAN
                           (AS ASSUMED BY ANTIGENICS INC.)
                              (Full Title of the Plan)
  
                                GARO H. ARMEN, PH.D.
                               Chief Executive Officer
                                   Antigenics Inc.
                            630 Fifth Avenue, Suite 2100
                              New York, New York 10111
                                   (212) 332-4774
              (Name, Address and Telephone Number of Agent for Service)
  
                                   with copies to:
                               PAUL M. KINSELLA, ESQ.
                                 Palmer & Dodge LLP
                                  One Beacon Street
                             Boston, Massachusetts 02108
                                   (617) 573-0100
  
                           CALCULATION OF REGISTRATION FEE
  PROPOSED MAXIMUM    PROPOSED MAXIMUM      AMOUNT OF
                                                              AMOUNT TO BE        OFFERING PRICE        AGGREGATE        REGISTRATION
    TITLE OF EACH CLASS OF SECURITIES TO BE REGISTERED        REGISTERED(1)         PER SHARE       OFFERING PRICE(2)         FEE
    --------------------------------------------------        -------------      ----------------   -----------------    ------------
  Aronex Pharmaceuticals, Inc. Amended and Restated 1989
  Stock Option Plan:
           Common Stock, $0.01 par value                      56,574 shares           $76.48            $4,326,780         $1,081.70
  
  Aronex Pharmaceuticals, Inc. Amended and Restated 1993
  Non-employee Director Stock Option Plan:
           Common Stock, $0.01 par value                      34,731 shares           $75.66            $2,627,747         $  656.94
  
  Aronex Pharmaceuticals, Inc. Amended and Restated 1998
  Stock Option Plan:
           Common Stock, $0.01 par value                      81,006 shares           $32.19            $2,607,583         $  651.90
                                                                                                                           =========
  Total                                                      172,311 shares                                                $2,390.54
  (1)  Pursuant to Rule 416 under the Securities Act of 1933, to the extent
       additional shares of our common stock may be issued or issuable as a result
       of a stock split or other distribution declared at any time by the Board of
       Directors while this registration statement is in effect, this registration
       statement is hereby deemed to cover all such additional shares of common
       stock.
  
  (2)  Estimated solely for the purpose of determining the registration fee and
       computed pursuant to Rule 457(h)(1). The proposed maximum aggregate
       offering price indicated is based on the weighted average price per share
       in effect for the outstanding options under the Aronex Pharmaceuticals,
       Inc. Amended and Restated 1989 Stock Option Plan ($76.48), the Aronex
       Pharmaceuticals, Inc. Amended and Restated 1993 Non-Employee Director Stock
       Option Plan ($75.66) and the Aronex Pharmaceuticals, Inc. 1998 Stock Option
       Plan ($32.19), as assumed by Antigenics Inc.
  2
                                       PART II
  
                 INFORMATION REQUIRED IN THE REGISTRATION STATEMENT
  
  ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.
  
  The following documents previously filed with the Securities and Exchange
  Commission are incorporated by reference herein and shall be deemed as part
  hereof:
  
              (a)   our Annual Report on Form 10-K for the fiscal year ended
                    December 31, 2000, filed with the SEC on March 28, 2001;
  
              (b)   all of our other reports filed pursuant to Section 13(a) or
                    15(d) of the Securities Exchange Act of 1934, as amended (the
                    "Exchange Act"), since December 31, 2000; and
  
              (c)   the description of our common stock contained in our
                    Registration Statement on Form 8-A filed on January 24, 2000,
                    including any amendment or report filed hereafter for the
                    purpose of updating such description.
  
  All documents filed after the date of this registration statement pursuant to
  Sections 13(a), 13(c), 14 and 15(d) of the Exchange Act and prior to the filing
  of a post-effective amendment that indicates that all shares of common stock
  offered hereunder have been sold or that deregisters all shares of common stock
  remaining unsold shall be deemed to be incorporated by reference herein and to
  be a part hereof from the date of the filing of such reports and documents. Any
  statement contained in a document incorporated or deemed to be incorporated by
  reference herein shall be deemed to be modified or superseded for purposes of
  this registration statement to the extent that a statement contained herein or
  in any other subsequently filed document that also is or is deemed to be
  incorporated by reference herein modifies or supersedes such statement. Any
  statement so modified or superseded shall not be deemed, except as so modified
  or superseded, to constitute as part of this registration statement.
  
  ITEM 4.  DESCRIPTION OF SECURITIES.
  
  Not applicable.
  
  ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.
  
  Not applicable.
  
  ITEM 6.  INDEMNIFICATION OF OFFICERS AND DIRECTORS.
  
  Section 145 of the Delaware General Corporation Law provides that a corporation
  may indemnify any person who was or is a party or is threatened to be made a
  party to any threatened, pending or completed action, suit or proceeding,
  whether civil, criminal, administrative or investigative, other than an action
  by or in the right of the corporation, by reason of the fact that the person is
  or was a director, officer, employee or agent of the corporation or is or was
  serving at the corporation's request as a director, officer, employee or agent
  of another corporation, partnership, joint venture, trust or other enterprise,
  against expenses, including attorneys' fees, judgments, fines and amounts paid
  in settlement actually and reasonably incurred by the person in connection with
  the action, suit or proceeding if the person acted in good faith and in a manner
  the person reasonably believed to be in or not opposed to the best interests of
  the corporation, and, with respect to any criminal action or proceeding, had no
  reasonable cause to believe the person's conduct was unlawful. The power to
  indemnify applies to actions brought by or in the right of
  
                                        II-1
  3
  the corporation as well, but only to the extent of expenses, including
  attorneys' fees but excluding judgments, fines and amounts paid in settlement,
  actually and reasonably incurred by the person in connection with the defense or
  settlement of the action or suit. In these actions no indemnification shall be
  made in the event of any adjudication of negligence or misconduct in the
  performance of his duties to the corporation, unless a court believes that in
  light of all the circumstances indemnification should apply.
  
  Article V of Antigenics' By-laws provides that Antigenics shall, to the extent
  legally permitted, indemnify each person who was or is a party or is threatened
  to be made a party to any threatened, pending or completed action, suit or
  proceeding by reason of the fact that he is or was, or has agreed to become, a
  director or officer of Antigenics, or is or was serving, or has agreed to serve,
  at the request of Antigenics, as a director, officer or trustee of, or in a
  similar capacity with, another corporation, partnership, joint venture, trust or
  other enterprises. The indemnification provided for in Article V is expressly
  not exclusive of any other rights to which those seeking indemnification may be
  entitled under any law, agreement or vote of stockholders or disinterested
  directors or otherwise, and shall inure to the benefit of the heirs, executors
  and administrators of such persons.
  
  Section 145(g) of the Delaware General Corporation Law and Article V of By-laws
  of Antigenics provide that the company shall have the power to purchase and
  maintain insurance on behalf of its officers, directors, employees and agents,
  against any liability asserted against and incurred by such persons in any such
  capacity.
  
  Antigenics has entered into indemnification agreements with each of its
  directors and executive officers and has obtained insurance covering its
  directors and officers against losses and insuring Antigenics against certain of
  its obligations to indemnify its directors and officers.
  
  Section 102(b)(7) of the General Corporation Law of the State of Delaware
  provides that a corporation may eliminate or limit the personal liability of a
  director to the corporation or its stockholders for monetary damages for breach
  of fiduciary duty as a director, provided that such provisions shall not
  eliminate or limit the liability of a director (i) for any breach of the
  director's duty of loyalty to the corporation or its stockholders, (ii) for acts
  or omissions not in good faith or which involve intentional misconduct or a
  knowing violation of law, (iii) under Section 174 of the General Corporation Law
  of the State of Delaware, or (iv) for any transaction from which the director
  derived an improper personal benefit. No such provision shall eliminate or limit
  the liability of a director for any act or omission occurring prior to the date
  when such provision becomes effective.
  
  Pursuant to the Delaware General Corporation Law, Section 6 of Article FIFTH of
  the Certificate of Incorporation of Antigenics eliminates a director's personal
  liability for monetary damages to Antigenics and its stockholders for breach of
  fiduciary duty as a director, except in circumstances involving a breach of the
  director's duty of loyalty to Antigenics or its stockholders, acts or omissions
  not in good faith, intentional misconduct, knowing violations of the law,
  self-dealing or the unlawful payment of dividends or repurchase of stock.
  
  ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.
  
  Not applicable.
  
                                        II-2
  4
  ITEM 8.  EXHIBITS.
  EXHIBIT      DESCRIPTION
      -------      -----------
      NUMBER
      ------
  4.1        Certificate of Incorporation of Antigenics Inc. Filed as Exhibit 3.1 to our Registration Statement
                   on Form S-1 (File No. 333-91747) and incorporated herein by reference.
  
        4.2        By-laws of Antigenics Inc. Filed as Exhibit 3.2 to our Registration Statement on Form S-1 (File No.
                   333-91747) and incorporated herein by reference.
  
        4.3        Form of Warrant to purchase Common Stock, together with a list of holders. Filed as Exhibit 4.1 to
                   our Registration Statement on Form S-1 (File No. 333-91747) and incorporated herein by reference.
  
        4.4        Form of Subscription Agreement, as amended, together with a list of parties thereto. Filed as
                   Exhibit 4.2 to our Registration Statement on Form S-1 (File No. 333-91747) and incorporated herein
                   by reference.
  
        5.1        Opinion of Palmer & Dodge LLP.  Filed herewith.
  
       23.1        Consent of KPMG LLP.  Filed herewith.
  
       23.2        Consent of PricewaterhouseCoopers LLP.  Filed herewith.
  
       23.3        Consent of Arthur Andersen LLP.  Filed herewith.
  
       23.4        Consent of Palmer & Dodge LLP. Included in the opinion filed as Exhibit 5.1.
  
       24.1        Power of Attorney.  Included on the signature page hereto.
  ITEM 9.  UNDERTAKINGS.
  
              (a)   The undersigned registrant hereby undertakes:
  
                    (1)   To file, during any period in which offers or sales are
                          being made, a post-effective amendment to this
                          registration statement:
  
                          (i)   To include any prospectus required by Section 10
                                (a)(3) of the Securities Act of 1933;
  
                          (ii)  To reflect in the prospectus any facts or events
                                arising after the effective date of this
                                registration statement (or the most recent
                                post-effective amendment thereof) which,
                                individually or in the aggregate, represents a
                                fundamental change in the information set forth in
                                this registration statement;
  
                          (iii) To include any material information with respect
                                to the plan of distribution not previously
                                disclosed in this registration statement or any
                                material change to such information in this
                                registration statement;
  
                                provided, however, that paragraphs (a) (1) (i) and
                                (a) (1) (ii) do not apply if the information
                                required to be included in a post-effective
                                amendment by
  
                                        II-3
  5
                                those paragraphs is contained in periodic reports
                                filed with or furnished to the Commission by the
                                registrant pursuant to Section 13 or Section 15(d)
                                of the Exchange Act of 1934 that are incorporated
                                by reference in this registration statement.
  
                    (2)   That, for the purpose of determining any liability under
                          the Securities Act of 1933, each such post-effective
                          amendment shall be deemed to be a new registration
                          statement relating to the securities offered therein,
                          and the offering of such securities at that time shall
                          be deemed to be the initial bona fide offering thereof.
  
                    (3)   To remove from registration by means of a post-effective
                          amendment any of the securities being registered which
                          remain unsold at the termination of the offering.
  
              (b)   The undersigned registrant hereby undertakes that, for
                    purposes of determining any liability under the Securities Act
                    of 1933, each filing of the registrant's annual report
                    pursuant to Section 13(a) or Section 15(d) of the Exchange Act
                    of 1934 that is incorporated by reference in this registration
                    statement shall be deemed to be a new registration statement
                    relating to the securities offered therein and the offering of
                    such securities at that time shall be deemed to be initial
                    bona fide offering thereof.
  
              (c)   Insofar as indemnification for liabilities arising under the
                    Securities Act of 1933 may be permitted to directors, officers
                    and controlling persons of the registrant pursuant to the
                    provisions referred to in Item 6 hereof, or otherwise, the
                    registrant has been advised that in the opinion of the
                    Securities and Exchange Commission such indemnification is
                    against public policy as expressed in the Securities Act of
                    1933 and is, therefore, unenforceable. In the event that a
                    claim for indemnification against such liabilities (other than
                    the payment by the registrant of expenses incurred or paid by
                    a director, officer or controlling person of the registrant in
                    the successful defense of any action, suit or proceeding) is
                    asserted by such director, officer, or controlling person in
                    connection with the securities being registered, the
                    registrant will, unless in the opinion of its counsel the
                    matter has been settled by controlling precedent, submit to a
                    court of appropriate jurisdiction the question whether such
                    indemnification by it is against public policy as expressed in
                    the Securities Act of 1933 and will be governed by the final
                    jurisdiction of such issue.
  
                                        II-4
  6
                                     SIGNATURES
  
  Pursuant to the requirements of the Securities Act of 1933, the registrant
  certifies that it has reasonable grounds to believe that it meets all of the
  requirements for filing on Form S-8 and has duly caused this Registration
  Statement to be signed on its behalf by the undersigned, thereunto duly
  authorized, in the Town of Woburn, Commonwealth of Massachusetts, as of
  September 18, 2001.
  
                                      ANTIGENICS INC.
  
                                      By:   /s/ Garo H. Armen, Ph.D.
                                      --------------------------------------------
                                            Garo H. Armen, Ph.D.
                                            Chief Executive Officer and
                                            Chairman of the Board of Directors
  
                                  POWER OF ATTORNEY
  
  We, the undersigned officers and directors of Antigenics Inc., hereby severally
  constitute and appoint Garo H. Armen, Ph.D. and Paul M. Kinsella and each of
  them singly, our true and lawful attorneys-in-fact, with full power to them in
  any and all capacities, to sign any and all amendments to this Registration
  Statement on Form S-8 (including any post-effective amendments thereto), and to
  file the same, with exhibits thereto and other documents in connection
  therewith, with the Securities and Exchange Commission, hereby ratifying and
  confirming all that each of said attorneys-in-fact may do or cause to be done by
  virtue hereof.
  
  Pursuant to the requirements of the Securities Act of 1933, this registration
  statement has been signed below by the following persons in the capacities and
  as of the dates indicated.
  Signature                                   Title                                       Date
  ---------                                   -----                                       ----
  /s/ Garo H. Armen, Ph.D.                    Chief Executive Officer and                 September 18, 2001
  ----------------------------------          Chairman of the Board of Directors
  Garo H. Armen, Ph.D.                        (Principal Executive Officer and
                                              Principal Financial and Accounting
                                              Officer)
  
  /s/ Pramod Srivastava, Ph.D.                Director                                    September 18, 2001
  ----------------------------------
  Pramod Srivastava, Ph.D.
  
  /s/ Noubar Afeyan, Ph.D.                    Director                                    September 18, 2001
  ----------------------------------
  Noubar Afeyan, Ph.D.
  
  /s/ Gamil de Chadarevian                    Vice Chairman of the Board                  September 18, 2001
  ----------------------------------          of Directors
  Gamil de Chadarevian
  
  /s/ Tom Dechaene                            Director                                    September 18, 2001
  ----------------------------------
  Tom Dechaene
  
  /s/ Martin Taylor                           Director                                    September 18, 2001
  ----------------------------------
  Martin Taylor
  
  /s/ Sanford M. Litvack                      Director                                    September 18, 2001
  ----------------------------------
  Sanford M. Litvack
  
                                              Director
  ----------------------------------
  Samuel Waksal, Ph.D.
  II-5
  7
                                    EXHIBIT INDEX
  EXHIBIT      DESCRIPTION
      -------      -----------
      NUMBER
      ------
  4.1        Certificate of Incorporation of Antigenics Inc. Filed as Exhibit 3.1 to our Registration
                   Statement on Form S-1 (File No. 333-91747) and incorporated herein by reference.
  
        4.2        By-laws of Antigenics Inc. Filed as Exhibit 3.2 to our Registration Statement on Form S-1 (File
                   No. 333-91747) and incorporated herein by reference.
  
        4.3        Form of Warrant to purchase Common Stock, together with a list of holders. Filed as Exhibit 4.1
                   to our Registration Statement on Form S-1 (File No. 333-91747) and incorporated herein by
                   reference.
  
        4.4        Form of Subscription Agreement, as amended, together with a list of parties thereto. Filed as
                   Exhibit 4.2 to our Registration Statement on Form S-1 (File No. 333-91747) and incorporated
                   herein by reference.
  
        5.1        Opinion of Palmer & Dodge LLP.  Filed herewith.
  
       23.1        Consent of KPMG LLP.  Filed herewith.
  
       23.2        Consent of PricewaterhouseCoopers LLP.  Filed herewith.
  
       23.3        Consent of Arthur Andersen LLP.  Filed herewith.
  
       23.4        Consent of Palmer & Dodge LLP. Included in the opinion filed as Exhibit 5.1.
  
       24.1        Power of Attorney.  Included on the signature page hereto.
  II-6