Form of Contingent Warrant



 Exhibit 4.2 
 NEITHER THESE SECURITIES NOR THE SECURITIES FOR WHICH THESE SECURITIES ARE EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM
REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE
EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH APPLICABLE STATE SECURITIES LAWS. THESE SECURITIES AND THE SECURITIES ISSUABLE UPON EXERCISE OF THESE SECURITIES MAY BE
PLEDGED IN CONNECTION WITH A BONA FIDE MARGIN ACCOUNT OR OTHER LOAN SECURED BY SUCH SECURITIES. 
 ANTIGENICS INC 
 UNIT WARRANT 
  

			
	Warrant No. U-	  	Dated: January 9, 2008

 Antigenics Inc., a Delaware corporation (the “Company”), hereby certifies
that, for value received,                      or its registered assigns (including permitted transferees, the
“Holder”), as registered owner of this warrant (the “Warrant”), is entitled to purchase from the Company up to a total of             
units (each a “Unit”), each Unit (as adjusted from time to time as provided in Section 9) to consist of (i) one share (a “Warrant Share”) of Common Stock (as defined below) and
(ii) one warrant (a “Share Warrant”), exercisable for ten years from the date of exercise of this Warrant, to purchase one share of Common Stock (a “Second Warrant Share”) at $3.00 per share in
the form attached here to as Exhibit A, at an exercise price equal to $3.00 per share (as adjusted from time to time as provided in Section 9, the “Exercise Price”), at any time and from time to time from
and after July 9, 2008 (the “Initial Exercise Date”) to and including January 9, 2010 (the “Expiration Date”), and subject to the following terms and conditions. 
 1. Definitions. The capitalized terms used herein and not otherwise defined shall have the meanings set forth below: 
 “Affiliate” of any specified Person means any other person or entity directly or indirectly controlling, controlled by or under
direct or indirect common control with such specified Person. For purposes of this definition, “control” means the power to direct the management and policies of such Person or firm, directly or indirectly, whether through
the ownership of voting securities, by contract or otherwise. 
 “At-the-Market Offerings” shall have the meaning
ascribed to such term in Rule 415(a)(4) of the Securities Act, or a successor thereto. 







 “Capital Raising Transactions” shall mean primary sales by the Company of shares
of Common Stock other than Excluded Transactions (as defined below). 
 “Commission” means the United States
Securities and Exchange Commission. 
 “Common Stock” means the common stock of the Company, $0.01 par value per
share. 
 “Eligible Market” means any of the New York Stock Exchange, the American Stock Exchange or Nasdaq (as
defined below), and any successor markets thereto. 
 “Exchange Act” means the Securities Exchange Act of 1934, as
amended. 
 “Excluded Transaction” shall mean (1) the transactions contemplated by this Agreement, including
the issuance of shares of Common Stock pursuant to the exercise of Warrants, (2) At-the-Market Offerings, (3) the issuance or sale of shares of Common Stock to directors, officers, employees, consultants, or advisors, pursuant to any
equity incentive or benefit plan approved (either before or after the date of this Agreement) by the Board of Directors of the Company, (4) the conversion, exercise or exchange of any convertible, exercisable or exchangeable securities or
rights outstanding on the date hereof that are listed on Schedule A attached hereto, (5) the issuance of shares of Common Stock in connection with any strategic licensing arrangement, corporate partnering transaction or similar
collaboration, or the conversion, exercise or exchange of any securities issued in connection with such transactions that are convertible into or exercisable or exchangeable for shares of Common Stock, provided that such transaction is not
consummated for the primary purpose of raising additional capital and (6) issuances of shares of Common Stock in connection with business combination transactions, including (i) mergers, (ii) consolidations, and (iii) purchases
of securities or assets, or the conversion, exercise, or exchange of any securities issued in such transactions that are convertible into or exercisable or exchangeable for Common Stock. 
 “Market Price” shall mean (i) if the principal trading market for such securities is an exchange, the average of the last
reported sale prices per share for the last ten previous Trading Days in which a sale was reported, as officially reported on any consolidated tape, (ii) if clause (i) is not applicable, the average of the closing bid price per share for
the last ten previous Trading Days as set forth by Nasdaq or (iii) if clauses (i) and (ii) are not applicable, the average of the closing bid price per share for the last ten previous Trading Days as set forth in the National
Quotation Bureau sheet listing for such securities. Notwithstanding the foregoing, if there is no reported sales price or closing bid price, as the case may be, on any of the ten Trading Days preceding the event requiring a determination of Market
Price hereunder, then the Market Price shall be determined in good faith after reasonable investigation by resolution of the Board of Directors of the Company. 
 “Nasdaq” means the Nasdaq Global Market or Nasdaq Capital Market, and any successor markets thereto. 
 “Other Securities” refers to any capital stock (other than Share Warrants) and other securities of the Company or any other Person which the Holder of this Warrant at any 

  

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time shall be entitled to receive, or shall have received, pursuant to the terms hereof upon the exercise of this Warrant, in lieu of or in addition to Share
Warrants and Warrant Shares. 
 “Person” means any court or other federal, state, local or other governmental
authority or other individual or corporation, partnership, trust, incorporated or unincorporated association, joint venture, limited liability company, joint stock company, government (or an agency or subdivision thereof) or other entity of any
kind. 
 “Trading Day” means (a) any day on which the Common Stock is listed or quoted and traded on any
Eligible Market or (b) if the Common Stock is not then quoted and traded on any Eligible Market, then a day on which trading occurs on the Nasdaq Global Market (or any successor thereto). 
 “Warrant Securities” shall initially mean Share Warrants and Warrant Shares and in addition may include Other Securities and
Substituted Property (as defined in Section 9(e)(x)) issued or issuable from time to time upon exercise of this Warrant. 
 2.
Registration of Warrant. The Company shall register this Warrant, upon records to be maintained by the Company for that purpose (the “Warrant Register”), in the name of the record Holder hereof from time to time. The
Company may deem and treat the registered Holder of this Warrant as the absolute owner hereof for the purpose of any exercise hereof or any distribution to the Holder, and for all other purposes. 
 3. Registration of Transfers. The Company shall register the transfer of any portion of this Warrant in the Warrant Register, upon surrender of
this Warrant, with the Form of Assignment attached hereto as Appendix A duly completed and signed, to the Company at its address specified herein. Upon any such registration and transfer, a new warrant in substantially the form of a
Warrant (any such new warrant, a “New Warrant”), evidencing the portion of this Warrant so transferred shall be issued to the transferee and a New Warrant evidencing the remaining portion of this Warrant not so transferred,
if any, shall be issued to the transferring Holder. The acceptance of the New Warrant by the transferee thereof shall be deemed the acceptance by such transferee of all of the rights and obligations of a holder of a Warrant. 
 4. Exercise and Duration of Warrant. 
 (a) This Warrant shall be exercisable, either in its entirety or for a portion of the number of Warrant Securities, by the registered Holder at any time and from time to time from and after the Initial Exercise Date to and including the
Expiration Date, subject to the remaining provisions of this Section 4. At 5:00 P.M. New York City time on the Expiration Date, the portion of this Warrant not exercised prior thereto shall be and become void and of no value, and
the Holder hereof shall have no right to purchase any additional Warrant Securities hereunder, except to the extent set forth in the remaining provisions of this Section 4. 
 (b) A Holder may exercise this Warrant by delivering to the Company, in accordance with Section 13, this Warrant, together with (i) an
exercise notice, in the form attached hereto as Appendix B (the “Exercise Notice”), appropriately completed and duly signed, and (ii) payment of the Exercise Price for the number of Warrant Securities as to
which this Warrant is being 

  

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exercised pursuant to a Cash Exercise (as set forth in Section 4(c) below), and the date such items are received by the Company is an
“Exercise Date.” Execution and delivery of an Exercise Notice in respect of less than all of the Warrant Securities issuable upon exercise of this Warrant shall result in the cancellation of the original Warrant and issuance
of a New Warrant evidencing the right to purchase the remaining number of Warrant Securities. 
 (c) Cash Exercise. The Holder shall
pay the Exercise Price by certified bank check payable to the order of the Company or by wire transfer of immediately available funds in accordance with the Company’s instructions (a “Cash Exercise”). 
 (d) This Warrant is only exercisable if, prior to the Expiration Date, the Company closes upon (i) a Capital Raising Transaction and/or
(ii) one or more At-the-Market Offering that result, in aggregate, in gross proceeds to the Company of at least $10 million (the date such threshold is crossed, the “At-the-Market Offering Event”); provided, however,
that (A) this Warrant will not be exercisable during the sixty (60) day period following the closing date of the first to occur of (x) a Capital Raising Transaction or (y) an At-the-Market Offering Event (the first to occur, a
“Triggering Event”) and (B) if a Triggering Event occurs on, or during the 60 days preceding, the Expiration Date, the Expiration Date shall automatically be extended for a period of ninety (90) days from the
Triggering Event. 
 (e) Notwithstanding anything to the contrary herein or in the Securities Purchase Agreement dated January 9, 2008
between the Company, the Holder, and other parties named therein (the “Securities Purchase Agreement”), the Holder agrees that in the event there is not an effective registration statement covering the Warrant Shares and the
Second Warrant Shares the sole and exclusive remedy of the Holder for a registration default with respect to the Warrant Shares and the Second Warrant Shares is for the Holder to seek specific performance, and in no event shall the Company be
required to pay any cash settlement, damages (liquidated or otherwise) for a registration default with respect to the Warrant Shares and the Second Warrant Shares. 
 (f) Except as otherwise provided for herein, this Warrant shall not entitle the Holder to any voting rights or other rights as a stockholder of the Company by virtue of the ownership hereof. 
 (g) Upon any exercise of this Warrant, which together with the exercise of any other Contingent Company Warrants (as defined in the Securities Purchase
Agreement) on the same day results in the payment of an aggregate exercise price of at least $6 million (A) the Company shall bring down the representations and warranties contained in Section 3 of the Securities Purchase Agreement,
(B) the Company shall deliver to the Holder an officers’ certificate certifying as to (A) above and (C) to the extent applicable, the Company shall deliver a new disclosure letter. 
 5. Delivery of Warrant Securities. 
 (a) Upon exercise of this Warrant, the Company shall promptly (but in no event later than three Trading Days after the Exercise Date) issue or cause to be issued and deliver or cause to be delivered to the Holder, in such name or names as
the Holder may designate, a certificate 

  

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for the Warrant Shares issuable upon such exercise (the “Certificate”) and a Share Warrant exercisable for Second Warrant Shares. The
Holder, or any Person so designated by the Holder to receive the Warrant Securities, shall be deemed to have become holder of record of such Warrant Securities as of the Exercise Date. 
 (b) Neither these securities nor the securities for which these securities are exercisable have been registered with the Commission or the securities
commission of any state in reliance upon an exemption from registration under the Securities Act, and, accordingly, may not be offered or sold except pursuant to an effective registration statement under the Securities Act or pursuant to an
available exemption from, or in a transaction not subject to, the registration requirements of the Securities Act and in accordance with applicable state securities laws. The Holder acknowledges and agrees that the Warrant may be sold only pursuant
to an applicable exemption from the registration requirements of the Securities Act and that the Warrant Securities may only be sold pursuant to an effective registration statement under the Securities Act or in accordance with any applicable
exemption from the registration requirements of the Securities Act. 
 (c) This Warrant is exercisable, either in its entirety or, from time
to time, for a portion of the number of Warrant Securities. Upon surrender of this Warrant following one or more partial exercises, the Company shall issue or cause to be issued, at its expense, a New Warrant evidencing the right to purchase the
remaining number of Warrant Securities. 
 (d) To the extent permitted by law, the Company’s obligations to issue and deliver Warrant
Securities in accordance with the terms hereof are absolute and unconditional, irrespective of any action or inaction by the Holder to enforce the same, any waiver or consent with respect to any provision hereof, the recovery of any judgment against
any Person or any action to enforce the same, or any setoff, counterclaim, recoupment, limitation or termination, or any breach or alleged breach by the Holder or any other Person of any obligation to the Company or any violation or alleged
violation of law by the Holder or any other Person, and irrespective of any other circumstance which might otherwise limit such obligation of the Company to the Holder in connection with the issuance of Warrant Securities. Nothing herein shall limit
the Holder’s right to pursue any other remedies available to it hereunder, in equity including, without limitation, a decree of specific performance and/or injunctive relief with respect to the Company’s failure to timely deliver Warrant
Securities upon exercise of this Warrant as required pursuant to the terms hereof. 
 6. Charges, Taxes and Expenses. Issuance and
delivery of Certificates and Share Warrants upon exercise of this Warrant shall be made without charge to the Holder for any issue or transfer tax, withholding tax, transfer agent fee or other incidental tax or expense in respect of the issuance of
such certificates and warrants, all of which taxes and expenses shall be paid by the Company; provided, however, that the Company shall not be required to pay any tax which may be payable in respect of any transfer involved in the
issue, delivery or registration of any certificates for certificates or warrants in a name other than that of the Holder and that the Holder will be required to pay any tax with respect to cash received in lieu of fractional shares. The Holder shall
be responsible for all other tax liability of the Holder that may arise as a result of holding or transferring this Warrant or receiving Warrant Securities upon exercise hereof. 
  

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 7. Replacement of Warrant. If this Warrant is mutilated, lost, stolen or destroyed, the Company,
at the sole expense of the Holder (such expenses, if any imposed by the Company to be reasonable), shall issue or cause to be issued in exchange and substitution for and upon cancellation hereof, or in lieu of and in substitution for this Warrant, a
New Warrant, but only upon receipt of evidence reasonably satisfactory to the Company of such loss, theft or destruction and customary and reasonable indemnity, if requested by the Company. 
 8. Reservation of Warrant Shares. The Company covenants that it will at all times reserve and keep available out of the aggregate of its
authorized but unissued and otherwise unreserved Common Stock, solely for the purpose of enabling it to issue Warrant Shares upon exercise of this Warrant as herein provided and Second Warrant Shares upon exercise of any Share Warrants issued or
issuable hereunder, the number of Warrant Shares and Second Warrant Shares which are then issuable and deliverable upon the exercise of this entire Warrant and any Share Warrants issuable hereunder, free from all taxes, liens, claims, encumbrances
with respect to the issuance of such Warrant Shares and Second Warrant Shares and will not be subject to any pre-emptive rights or similar rights (taking into account the adjustments and restrictions of Section 9 hereof). The Company
covenants that all Warrant Shares and Second Warrant Shares so issuable and deliverable shall, upon issuance and the payment of the applicable Exercise Price in accordance with the terms hereof, be duly and validly authorized, issued, fully paid and
nonassessable. The Company will take all such action as may be necessary to assure that such shares of Common Stock may be issued as provided herein without violation of any applicable law or regulation, or of any requirements of any securities
exchange or automated quotation system upon which the Common Stock may be listed or quoted, as the case may be. 
 9. Certain
Adjustments. The Exercise Price and number of Warrant Securities issuable upon exercise of this Warrant are subject to adjustment from time to time as set forth in this Section 9. 
 (a) Stock Dividends. If the Company, at any time while this Warrant is outstanding, pays a dividend on its Common Stock payable in additional
shares of Common Stock or otherwise makes a distribution on any class of capital stock that is payable in shares of Common Stock, then in each such case the Exercise Price and the exercise price of the Share Warrants shall be multiplied by a
fraction, (A) the numerator of which shall be the number of shares of Common Stock outstanding immediately prior to the opening of business on the day after the record date for the determination of stockholders entitled to receive such dividend
or distribution and (B) the denominator of which shall be the number of shares of Common Stock outstanding immediately after the distribution date of such dividend or distribution. Any adjustment made pursuant to this Section 9(a)
shall become effective immediately after the record date for the determination of stockholders entitled to receive such dividend or distribution; provided, however, that if following such record date the Company rescinds or modifies such
dividend or distribution, the Exercise Price and the exercise price of the Share Warrants shall be appropriately adjusted (as of the date that the Company effectively rescinds or modifies such dividend or distribution) to take into account the
effect of such rescinded or modified dividend or distribution on the Exercise Price and the exercise price of the Share Warrants pursuant to this Section 9(a). 
 (b) Stock Splits. If the Company, at any time while this Warrant is outstanding, 

  

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(i) subdivides outstanding shares of Common Stock into a larger number of shares, or (ii) combines outstanding shares of Common Stock into a
smaller number of shares, then in each such case the Exercise Price and the exercise price of the Share Warrants shall be multiplied by a fraction, (A) the numerator of which shall be the number of shares of Common Stock outstanding immediately
before such event and (B) the denominator of which shall be the number of shares of Common Stock outstanding immediately after such event. Any adjustment pursuant to this Section 9(b) shall become effective immediately after the
effective date of such subdivision or combination. 
 (c) Reclassifications. A reclassification of the Common Stock (other than any
such reclassification in connection with a merger or consolidation to which Section 9(e) applies) into shares of any other class of stock shall be deemed: 
 (i) a distribution by the Company to the holders of its Common Stock of such shares of such other class of stock for the purposes and within the meaning of this Section 9; and 
 (ii) if the outstanding shares of Common Stock shall be changed into a larger or smaller number of shares of Common Stock as part of such
reclassification, such change shall be deemed a subdivision or combination, as the case may be, of the outstanding shares of Common Stock for the purposes and within the meaning of Section 9(b). 
 (d) Other Distributions. If the Company, at any time while this Warrant is outstanding, distributes to holders of Common Stock (i) evidences
of its indebtedness, (ii) shares of any class of capital stock, (iii) rights or warrants to subscribe for or purchase any shares of any class of capital stock or (iv) any other asset, other than a distribution of Common Stock covered
by Section 9(a), (in each case, “Distributed Property”), then in each such case the Exercise Price and the exercise price of the Share Warrants in effect immediately prior to the record date fixed for
determination of stockholders entitled to receive such distribution (and the Exercise Price and the exercise price of the Share Warrants thereafter applicable) shall be adjusted (effective on and after such record date) to equal the product of such
Exercise Price or exercise price of the Share Warrants, as applicable, multiplied by a fraction, (A) the numerator of which shall be Market Price on such record date less the then fair market value of the Distributed Property distributed in
respect of one outstanding share of Common Stock, which, if the Distributed Property is other than cash or marketable securities, shall be as reasonably determined in good faith by the Board of Directors of the Company whose determination shall be
described in a board resolution, and (B) the denominator of which shall be the Market Price on such record date; provided, however, that if following the record date for such distribution the Company rescinds or modifies such
distribution, the Exercise Price and the exercise price of the Share Warrants shall be appropriately adjusted (as of the date that the Company effectively rescinds or modifies such distribution) to take into account the effect of such rescinded or
modified distribution on the Exercise Price and the exercise price of the Share Warrants, as applicable, pursuant to this Section 9(d). 
  

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 (e) Fundamental Transactions. If, at any time while this Warrant is outstanding, (i) the
Company effects any merger or consolidation of the Company with or into another Person, (ii) the Company effects any sale of all or substantially all of its assets or a majority of its stock acquired by a third party, in each case in one or a
series of related transactions, (iii) any tender offer or exchange offer by another Person is completed pursuant to which all or substantially all of the holders of Common Stock are permitted to tender or exchange their shares for other
securities, cash or property or (iv) there shall occur any merger of another Person into the Company whereby the Common Stock is cancelled, converted or reclassified into or exchanged for other securities, cash or property (in any such case, a
“Fundamental Transaction”), then, as a condition to the consummation of such Fundamental Transaction, the Company shall (or, in the case of any Fundamental Transaction in which the Company is not the surviving entity, the
Company shall take all reasonable steps to cause such other Person to) execute and deliver to the Holder of this Warrant a written instrument providing that: 
 (x) so long as this Warrant remains outstanding, upon the exercise hereof at any time on or after the consummation of such Fundamental Transaction and on such terms and subject to such conditions as shall be nearly
equivalent as may be practicable to the provisions set forth in this Warrant, this Warrant shall be exercisable into, in lieu of Share Warrants and Warrant Shares issuable upon such exercise prior to such consummation, (i) the securities or
other property (the “Substituted Property”) that would have been received in connection with such Fundamental Transaction by a holder of the number of shares of Common Stock into which this Warrant was exercisable immediately prior to such
Fundamental Transaction and (ii) a warrant exercisable for the amount of Substituted Property that would have been received in connection with such Fundamental Transaction by a holder of the number of shares of Common Stock into which the Share
Warrants subject to this Warrant at such time was exercisable immediately prior to such Fundamental Transaction, assuming such holder of Common Stock: 
 (A) is not a Person with which the Company consolidated or into which the Company merged or which merged into the Company or to which such sale or transfer was made, as the case may be (a “Constituent
Person”), or an Affiliate of a Constituent Person; and 
 (B) failed to exercise such Holder’s rights of election, if any,
as to the kind or amount of securities, cash and other property receivable in connection with such Fundamental Transaction (provided, however, that if the kind or amount of securities, cash or other property receivable in connection with such
Fundamental Transaction is not the same for each share of Common Stock held immediately prior to such Fundamental Transaction by a Person other than a Constituent Person or an Affiliate thereof and in respect of which such rights of election shall
not have been exercised (a “Non-Electing Share”), then, for the purposes of this Section 9(e), the kind and amount of securities, cash and other property receivable in connection with such Fundamental Transaction
by each Non-Electing Share shall be deemed to be the kind and amount so receivable per share by a plurality of the Non-Electing Shares); and 
 (y) the rights and obligations of the Company (or, in the event of a transaction in which the Company is not the surviving Person, such other Person) and the Holder in respect of Substituted Property shall be as nearly equivalent as may be
practicable to the rights and obligations of the Company and Holder in respect of Common Stock hereunder. 
  

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 Such written instrument shall provide for adjustments which, for events subsequent to the effective date
of such written instrument, shall be as nearly equivalent as may be practicable to the adjustments provided for in this Section 9. The above provisions of this Section 9(e) shall similarly apply to successive Fundamental
Transactions. 
 (f) Adjustment of Warrant Securities. Simultaneously with any adjustment to the Exercise Price and/or the exercise
price of the Share Warrants pursuant to paragraphs (a) through (d) of this Section 9, the number of Warrant Securities that may be purchased upon exercise of this Warrant shall be increased or decreased proportionately, so that
after such adjustment the aggregate Exercise Price payable hereunder for the increased or decreased number of Warrant Securities shall be the same as the aggregate Exercise Price payable for the Warrant Securities immediately prior to such
adjustment. 
 (g) Calculations. All calculations under this Section 9 shall be made to the nearest cent or the nearest
1/100th of a share, as applicable. The number of shares of Common Stock outstanding at any given time shall not include shares owned or held by or for the account of the Company, and the disposition of any such shares shall be considered an issue or
sale of Common Stock. 
 (h) Adjustments. Notwithstanding any provision of this Section 9, no adjustment of the Exercise
Price or the exercise price of the Share Warrants shall be required if such adjustment is less than $0.01; provided, however, that any adjustments which by reason of this Section 9(h) are not required to be made shall be carried
forward and taken into account for purposes of any subsequent adjustment required to be made hereunder. 
 (i) Notice of Adjustments.
Upon the occurrence of each adjustment pursuant to this Section 9, the Company will promptly deliver to the Holder a certificate executed by the Company’s Chief Financial Officer setting forth, in reasonable detail, the event
requiring such adjustment and the method by which such adjustment was calculated, the adjusted Exercise Price and adjusted exercise price of the Share Warrants and the adjusted number or type of Warrant Shares, Share Warrants or other securities
issuable upon exercise of this Warrant (as applicable). The Company will retain at its office copies of all such certificates and cause the same to be available for inspection at said office during normal business hours by the Holder or any
prospective purchaser of the Warrant designated by the Holder. 
 (j) Notice of Corporate Events. If the Company (i) declares a
dividend or any other distribution of cash, securities or other property in respect of its Common Stock, including, without limitation, any granting of rights or warrants to subscribe for or purchase any capital stock of the Company or any
subsidiary of the Company, (ii) authorizes, approves, enters into any agreement contemplating, or solicits stockholder approval for, any Fundamental Transaction or (iii) authorizes the voluntary dissolution, liquidation or winding up of
the affairs of the Company, then the Company shall deliver to the Holder a notice describing the material terms and conditions of such transaction at least 15 Trading Days prior to the applicable record or effective date on which a Person would need
to hold Common Stock in order to participate in or vote with respect to such transaction, and the Company will take all steps reasonably necessary in order to ensure that the Holder is given the practical opportunity to exercise this Warrant prior
to such time so as to participate in or vote with respect to such transaction; provided, however, 

  

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that the failure to deliver such notice or any defect therein shall not affect the validity of the corporate action required to be described in such notice.

 10. Fractional Shares. The Company shall not be required to issue or cause to be issued fractional Warrant Shares on the exercise
of this Warrant. If any fraction of a Warrant Share would, except for the provisions of this Section 10, be issuable upon exercise of this Warrant, the Company shall make a cash payment to the Holder equal to (a) such fraction
multiplied by (b) the Market Price on the Exercise Date of one full Warrant Share. 
 11. Listing on Securities Exchanges. The
Company has agreed to list, and will use its reasonable best efforts to maintain the listing of, the Warrant Shares and Second Warrant Shares on Nasdaq consistent with the terms of the Securities Purchase Agreement. In furtherance and not in
limitation of any other provision of this Warrant, if the Company at any time shall list any Common Stock on any Eligible Market other than Nasdaq, the Company will use its reasonable best efforts, at its expense, to simultaneously list the Warrant
Shares and the Second Warrant Shares (and use its reasonable best efforts to maintain such listing) on such Eligible Market, upon official notice of issuance following the exercise of this Warrant; and the Company will so list, register and use its
reasonable best efforts to maintain such listing on any Eligible Market any Other Securities, if and at the time that any securities of like class or similar type shall be listed on such Eligible Market by the Company. 
 12. Remedies. The Company stipulates that the remedies at law of the Holder of this Warrant in the event of any default or threatened default by
the Company in the performance of or compliance with any of the terms of this Warrant are not and will not be adequate, and that such terms may be specifically enforced by a decree for the specific performance of any agreement contained herein or by
an injunction against a violation of any of the terms hereof or otherwise. 
 13. Notices. Any and all notices or other communications
or deliveries hereunder (including without limitation any Exercise Notice) shall be in writing and shall be mailed by certified mail, return receipt requested, or by a nationally recognized courier service or delivered (in person or by facsimile),
against receipt to the party to whom such notice or other communication is to be given. Any notice or other communication given by means permitted by this Section 13 shall be deemed given at the time of receipt thereof. The address for
such notices or communications shall be as set forth below: 
  

			
	If to the Company:	 	Antigenics Inc.
		 	162 Fifth Avenue, Suite 900,
		 	New York, New York 10010
		
	If to the Holder:	 	[Add Address]

 Or such other address as is provided to such other party in accordance with this Section 13.

 14. Warrant Agent. The Company shall serve as warrant agent under this Warrant. Upon a prompt written notice to the Holder, the
Company may appoint a new warrant agent. 

  

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Any Person into which any new warrant agent may be merged, any Person resulting from any consolidation to which any new warrant agent shall be a party or any
Person to which any new warrant agent transfers substantially all of its corporate trust or shareholders services business shall be a successor warrant agent under this Warrant without any further act. Any such successor warrant agent shall promptly
cause notice of its succession as warrant agent to be mailed (by first class mail, postage prepaid) to the Holder at the Holder’s last address as shown on the Warrant Register. 
 15. Miscellaneous. 
 (a) This Warrant
may be assigned by the Holder. This Warrant may not be assigned by the Company, except to a successor in the event of a Fundamental Transaction. This Warrant shall be binding on and inure to the benefit of the parties hereto and their respective
successors and assigns. Subject to the preceding sentence, nothing in this Warrant shall be construed to give to any Person other than the Company and the Holder any legal or equitable right, remedy or cause of action under this Warrant. This
Warrant may be amended only in writing signed by the Company and the Holder and their successors and assigns. 
 (b) The Company will not, by
amendment of its governing documents or through any reorganization, transfer of assets, consolidation, merger, dissolution, issue or sale of securities or any other voluntary action, avoid or seek to avoid the observance or performance of any of the
terms of this Warrant or the Share Warrants, but will at all times in good faith assist in the carrying out of all such terms and in the taking of all such action as may be necessary or appropriate in order to protect the rights of the Holder
against impairment. Without limiting the generality of the foregoing, the Company (i) will not increase the par value of any Warrant Shares or Second Warrant Shares above the amount payable therefor upon exercise thereof, and (ii) will
take all such action as may be reasonably necessary or appropriate in order that the Company may validly and legally issue fully paid and nonassessable Warrant Shares on the exercise of this Warrant and Second Warrant Shares on exercise of the Share
Warrants, free from all taxes, liens, claims and encumbrances and (iii) will not close its shareholder books or records in any manner which interferes with the timely exercise of this Warrant or the Share Warrants. 
  

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 (c) This Warrant shall be governed by and construed and enforced in accordance with the laws of the State
of New York. Each party hereby irrevocably submits to the exclusive jurisdiction of the state and Federal courts sitting in the City of New York, Borough of Manhattan, for the adjudication of any dispute hereunder or in connection herewith or with
any transaction contemplated hereby or discussed herein, and hereby irrevocably waives, and agrees not to assert in any suit, action or proceeding that it is not personally subject to the jurisdiction of any such court or that such suit, action or
proceeding is improper. Each party hereby irrevocably waives personal service of process and consents to process being served in any such suit, action or proceeding by mailing a copy thereof via registered or certified mail or overnight delivery
(with evidence of delivery) to such party at the address in effect for notices to it under this Warrant and agrees that such service shall constitute good and sufficient service of process and notice thereof. Nothing contained herein shall be deemed
to limit in any way any right to serve process in any manner permitted by law. THE PARTIES HEREBY WAIVE ALL RIGHTS TO A TRIAL BY JURY. 
 (d)
Neither party shall be deemed in default of any provision of this Warrant, to the extent that performance of its obligations or attempts to cure a breach hereof are delayed or prevented by any event reasonably beyond the control of such party,
including, without limitation, war, hostilities, acts of terrorism, revolution, riot, civil commotion, national emergency, strike, lockout, unavailability of supplies, epidemic, fire, flood, earthquake, force of nature, explosion, embargo, or any
other Act of God, or any law, proclamation, regulation, ordinance, or other act or order of any court, government or governmental agency, provided that such party gives the other party written notice thereof promptly upon discovery thereof
and uses reasonable best efforts to cure or mitigate the delay or failure to perform. 
 (e) The headings herein are for convenience only, do
not constitute a part of this Warrant and shall not be deemed to limit or affect any of the provisions hereof. 
 (f) In case any one or more
of the provisions of this Warrant shall be deemed invalid or unenforceable in any respect, the validity and enforceability of the remaining terms and provisions of this Warrant shall not in any way be affected or impaired thereby and the parties
will attempt in good faith to agree upon a valid and enforceable provision which shall be a commercially reasonable substitute therefor, and upon so agreeing, shall incorporate such substitute provision in this Warrant. 
 [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK, 
 SIGNATURE PAGE FOLLOWS] 
  

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 IN WITNESS WHEREOF, the Company has caused this Warrant to be duly executed by its authorized officer as
of the date first indicated above. 
  

			
	ANTIGENICS INC.
		
	By:	 	  

	Name:	 	Shalini Sharp
	Title:	 	Chief Financial Officer


  

 [UNIT WARRANT] 








 APPENDIX A 
 FORM OF ASSIGNMENT 
 (to be completed and signed only upon transfer of Warrant) 
 FOR VALUE RECEIVED, the undersigned hereby sells, assigns and transfers unto
                                        
                     the right represented by the within Warrant to purchase
                                        
shares of Common Stock of Antigenics Inc. and warrants to acquire an additional                      shares of Common Stock of Antigenics Inc.
to which the within warrant relates and appoints
                                        
                     attorney to transfer said right on the books of Antigenics Inc. with full power of substitution in the premises. 

 

					
	Dated:                     	 		 	  

		 		 	(Signature must conform in all respects to name of Holder as specified on face of the Warrant)
			
		 		 	Address of Transferee:
			
		 		 	  

			
		 		 	  

			
		 		 	  

			
	In the presence of:	 		 	
			
	  
	 		 	








 APPENDIX B 
 FORM OF EXERCISE NOTICE 
 (To be executed by the Holder to exercise the right to purchase shares of Common Stock under the
foregoing Warrant) 
  

	To:	Antigenics Inc. 

 The undersigned is the Holder of Warrant No.
[            ] (the “Warrant”) issued by Antigenics Inc., a Delaware corporation (the “Company”). Capitalized terms used herein and not otherwise defined have the
respective meanings set forth in the Warrant. 
  

	 	1.	The Warrant is currently exercisable to purchase a total of
                     Warrant Shares and Share Warrants. 

  

	 	2.	The undersigned Holder hereby exercises its right to purchase
                     Warrant Shares and Share Warrants pursuant to the Warrant. 

  

	 	3.	The Holder intends that payment of the Exercise Price shall be in cash: 

  

	 	4.	The Holder shall pay the sum of $                     to the Company in
accordance with the terms of the Warrant. 

  

	 	5.	Pursuant to this exercise, the Company shall deliver to the Holder
                     Warrant Shares and Share Warrants in accordance with the terms of the Warrant. 

  

	 	6.	Following this exercise, the Warrant shall be exercisable to purchase a total of
                     Warrant Shares and Share Warrants. 

  

							
	Dated:                     	 		 	Name of Holder:
				
		 		 	(Print)	 	  

				
		 		 	By:	 	  

				
		 		 	Title:	 	  

				
		 		 		 	(Signature must conform in all respects to name of Holder as specified on face of the Warrant)








 EXHIBIT A 
 FORM OF SHARE WARRANT 
  

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 SCHEDULE A 
 OUTSTANDING CONVERTIBLE OR EXCHANGEABLE 
 SECURITIES OR OTHER RIGHTS 
 Stock-Based Compensation as described in Note D to the Unaudited Condensed Consolidated Financial Statements of Form 10-Q for the quarter ended September 30, 2007.

 Class B Convertible Preferred Stock as described in Note H to the Unaudited Condensed Consolidated Financial Statements of Form 10-Q for the quarter ended
September 30, 2007. 
 Senior Secured Convertible Notes due 2011 as described in the Management’s Discussion and Analysis of Financial Condition
and Results of Operations section of the Form 10-Q for the quarter ended September 30, 2007 and Note 15 to the Consolidated Financial Statements of Form 10-K for the year ended December 31, 2006. 
 Convertible Senior Notes due 2025, with the possibility of forced early redemption starting in 2012, as described in Note 15 to the Consolidated Financial Statements of
Form 10-K for the year ended December 31, 2006. 
 Series A Convertible Preferred Stock as described in Note 10 to the Consolidated Financial Statements
of Form 10-K for the year ended December 31, 2006. 
  

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