To Purchase 10,000 Shares of Common Stock of TENGION, INC. (the Company)

Exhibit 4.6

THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR ANY STATE SECURITIES LAWS. THEY MAY NOT BE SOLD OR OFFERED FOR SALE IN THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT AS TO THE SECURITIES UNDER SAID ACT AND ANY APPLICABLE STATE SECURITIES LAWS OR THE AVAILABILITY OF AN EXEMPTION FROM REGISTRATION UNDER SAID ACT AND ANY APPLICABLE STATE SECURITIES LAWS.

STOCK SUBSCRIPTION WARRANT

To Purchase 10,000 Shares of Common Stock of

TENGION, INC. (the “Company”)

DATE OF INITIAL ISSUANCE: September 1, 2005

THIS CERTIFIES THAT for value received, APCO Worldwide Inc., a Delaware corporation, or its registered assigns (the “Holder”) is entitled to purchase from the Company, at any time during the Term of this Warrant, Ten Thousand (10,000) shares of common stock, $.001 par value, of the Company (the “Common Stock”), at the Warrant Price, payable in lawful money of the United States of America to be paid upon the exercise hereof. The exercise of this Warrant shall be subject to the provisions, limitations and restrictions herein contained, and may be exercised in whole or in part.

1.     Definitions.

For all purposes of this Warrant, the following terms shall have the meanings indicated:

1.1    Common Stock - shall mean and include the Company’s authorized Common Stock, $.001 par value, as constituted at the date hereof.

1.2    Current Market Price - shall mean, at any date and with respect to one share of Common Stock, the average of the daily closing prices for the 30 consecutive business days ending five business days before the day in question (as adjusted for any stock dividend, split, combination or reclassification that took effect during such 30 business day period). The closing price for each day shall be the last reported sales price or, in case no such reported sales took place on such day, the average of the last reported bid and asked prices, in either case on the principal national securities exchange on which the Common Stock is listed or admitted to trading or as reported by Nasdaq (or if the Common Stock is not at the time listed or admitted for trading on any such exchange or if the prices of the Common Stock are not reported by Nasdaq then such price shall be equal to the average of the last reported bid and asked prices on such day as reported by The National Quotation Bureau Incorporated or any similar reputable quotation and reporting service, if such quotation is not reported by The National Quotation Bureau Incorporated); provided, however, that if the Common Stock is not traded in such manner that the quotations referred to herein are available for the period required hereunder, the Current Market Price shall be determined in good faith by the Board of Directors of the Company or, if such determination cannot be made, by a nationally recognized independent investment banking firm selected by the Board of Directors of the Company (or if such selection cannot be made, by a nationally recognized independent investment banking firm selected by the American Arbitration Association in accordance with its rules).

1.3    Securities Act - shall mean the Securities Act of 1933, as amended.

1.4    Term of this Warrant - shall mean the period beginning on the date of initial issuance hereof and ending on the tenth anniversary of such date.

1.5    Warrant Price - shall mean initially $0.16 per share.

1.6    Warrant Shares - shall mean shares of Common Stock purchased or purchasable by the Holder of this Warrant upon the exercise hereof.

2.     Exercise of Warrant. To exercise this Warrant in whole or in part (but not as to any fractional share of Common Stock), the Holder shall deliver to the Company at its office referred to in Section 11 hereof at any time and from time to time during the Term of this Warrant: (i) the Notice of Exercise in the form attached hereto, (ii) cash, certified or official bank check payable to the order of the Company, wire transfer of funds to the Company’s account, or evidence of any indebtedness of the Company to the Holder (or any combination of any of the foregoing) in the amount of the Warrant Price for each share being purchased, and (iii) this Warrant. In the event of any exercise of the rights represented by this Warrant, a certificate or certificates for the shares of Common Stock so purchased, registered in the name of the Holder or such other name or names as may be designated by the Holder, shall be delivered to the Holder hereof within a reasonable time, not exceeding fifteen business days, after the rights represented by this Warrant shall have been so exercised; and, unless this Warrant has expired, a new Warrant representing the number of shares (except a remaining fractional share), if any, with respect to which this Warrant shall not then have been exercised shall also be issued to the Holder hereof within such time. The person in whose name any certificate for shares of Common Stock is issued upon exercise of this Warrant shall for all purposes be deemed to have become the holder of record of such shares on the date on which the Warrant was surrendered and payment of the Warrant Price and any applicable taxes was made, irrespective of the date of delivery of such certificate, except that, if the date of such surrender and payment is a date when the stock transfer books of the Company are closed, such person shall be deemed to have become the holder of such shares at the close of business on the next succeeding date on which the stock transfer books are open.

3.     Representations and Warranties. By acceptance of this Warrant, the Holder represents and warrants to the Company as follows:

3.1    The Holder is aware of the Company’s business affairs and financial condition, and has acquired information about the Company sufficient to reach an informed and knowledgeable decision to acquire this Warrant. The Holder is acquiring this Warrant for its own account for investment purposes only and not with a view to, or for the resale in connection with, any “distribution” thereof in violation of the Act.

3.2    The Holder understands that this Warrant has not been registered under the Act in reliance upon a specific exemption therefrom, which exemption depends upon, among other things, the bona fide nature of the holder’s investment intent as expressed herein.

3.3    The Holder further understands that this Warrant must be held indefinitely unless subsequently registered under the Securities Act and qualified under any applicable state securities laws, or unless exemptions from registration and qualification are otherwise available. The Holder is aware of the provisions of Rule 144, promulgated under the Securities Act.

3.4    The holder is an “accredited investor” as such term is defined in Rule 501 of Regulation D promulgated under the Securities Act.

4.     Adjustment of Number of Shares. Upon each adjustment of the Warrant Price as provided in Section 5, the Holder shall thereafter be entitled to purchase, at the Warrant Price resulting from such adjustment, the number of shares (calculated to the nearest tenth of a share) obtained by multiplying the Warrant Price in effect immediately prior to such adjustment by the number of shares purchasable pursuant hereto immediately prior to such adjustment and dividing the product thereof by the Warrant Price resulting from such adjustment.

5.     Adjustment of Warrant Price. The Warrant Price shall be subject to adjustment from time to time as follows:

5.1    Stock Dividends, Subdivisions, Split-Ups. If, at any time during the Term of this Warrant, the number of shares of Common Stock outstanding is increased by a stock dividend payable in shares of Common Stock or by a subdivision or split-up of shares of Common Stock, then, following the record date fixed for the determination of holders of Common Stock entitled to receive such stock dividend, subdivision or split-up, the Warrant Price shall be appropriately decreased so that the number of shares of Common Stock issuable upon the exercise hereof shall be increased in proportion to such increase in outstanding shares.

5.2    Stock Combinations. If, at any time during the Term of this Warrant, the number of shares of Common Stock outstanding is decreased by a combination of the outstanding shares of Common Stock, then, following the record date for such combination, the Warrant Price shall be appropriately increased so that the number of shares of Common Stock issuable upon the exercise hereof shall be decreased in proportion to such decrease in outstanding shares.

5.3    General.

(a)     All calculations of Warrant Price under this Section 5 shall be made to the nearest cent.

(b)     Adjustments made pursuant to Sections 5.1 or 5.2 above shall be made on the date such dividend, subdivision, split-up or combination, as the case may be, is made, and shall become effective at the opening of business on the business day next following the record date for the determination of stockholders entitled to such dividend, subdivision, split-up or combination.

(c)     In any case in which the provisions of this Section 5 require that an adjustment become effective immediately after a record date for an event, the Company may defer until the occurrence of such event issuing to the Holder of all or any part of this Warrant which is exercised after such record date and before the occurrence of such event the additional shares of capital stock issuable upon such exercise by reason of the adjustment required by such event over and above the shares of capital stock issuable upon such exercise before giving effect to such

adjustment exercise; provided, however, that the Company shall deliver to such Holder a due bill or other appropriate instrument evidencing such Holder’s right to receive such additional shares upon the occurrence of the event requiring such adjustment.

6.     Ownership.

6.1    Ownership of This Warrant. The Company may deem and treat the person in whose name this Warrant is registered as the holder and owner hereof (notwithstanding any notations of ownership or writing hereon made by anyone other than the Company) for all purposes and shall not be affected by any notice to the contrary until presentation of this Warrant for registration of transfer as provided in this Section 6.

6.2    Replacement. Upon receipt by the Company of evidence reasonably satisfactory to it of the loss, theft or destruction, and, in such case, of indemnity or security reasonably satisfactory to it, and upon surrender of this Warrant if mutilated, the Company will make and deliver a new Warrant of like tenor, in lieu of this Warrant; provided that if the Holder hereof is an instrumentality of a state or local government or an institutional holder or a nominee for such an instrumentality or institutional holder, an irrevocable agreement of indemnity by such Holder shall be sufficient for all purposes of this Section 6, and no evidence of loss or theft or destruction shall be necessary. This Warrant shall be promptly cancelled by the Company upon the surrender hereof in connection with any transfer or replacement. Except as otherwise provided above, in the case of the loss, theft or destruction of a Warrant, the Company shall pay all expenses, taxes and other charges payable in connection with any transfer or replacement of this Warrant, other than stock transfer taxes (if any) payable in connection with a transfer of this Warrant, which shall be payable by the Holder.

6.3    Transfer Restrictions. This Warrant and all rights hereunder are transferable in whole or in part upon the books of the Company by the Holder hereof in person or by its duly authorized attorney, and a new Warrant or Warrants, of the same tenor as this Warrant but registered in the name of the transferee or transferees (and in the name of the Holder, if a partial transfer is effected) shall be made and delivered by the Company upon surrender of this Warrant duly endorsed, at the office of the Company referred to in Section 11 hereof. If, at the time of any transfer or exchange of this Warrant, this Warrant is not registered under the Securities Act, the Company may require, as a condition of such transfer or exchange, that the Holder or transferee of such Warrant furnish an opinion of counsel reasonably acceptable to the Company or a “no action” or similar letter from the Securities and Exchange Commission to the effect that such transfer or exchange may be made without registration under the Securities Act. In the case of such transfer or exchange, the Company may require a written statement that such Warrant is being acquired for investment and not with a view to the distribution therefore. Holder will not transfer this Warrant and the rights hereunder except in compliance with federal and state securities laws.

6.4    Transfer Restriction Legend. Each certificate for Warrant Shares shall bear the following legend (and any additional legend required by (i) any applicable state securities laws and (ii) any securities exchange upon which such Warrant Shares may, at the time of such exercise, be listed) on the face thereof unless at the time of exercise such Warrant Shares shall be registered under the Securities Act:

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933. THESE SECURITIES MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM UNDER SAID ACT.

Any certificate issued at any time in exchange or substitution for any certificate bearing such legend (except a new certificate issued upon completion of a public distribution under a registration statement of the securities represented thereby) shall also bear such legend unless, in the opinion of counsel for the holder thereof (which counsel shall be reasonably satisfactory to counsel for the Company) the securities represented thereby are not, at such time, required by law to bear such legend.

6.5    Warrant Shares Subject to Certain Agreements. The Warrant Shares shall be subject to the terms of the Stockholders’ Agreement, dated as of August 16, 2004, as amended, among the Company and certain stockholders of the Company.

7.     Mergers, Consolidation, Sales. In the case of any proposed consolidation or merger of the Company with another entity, or the proposed sale of all or substantially all of its assets to another person or entity, or any proposed reorganization or reclassification of the capital stock of the Company, then, as a condition of such consolidation, merger, sale, reorganization or reclassification, lawful and adequate provision shall be made whereby the Holder of this Warrant shall thereafter have the right to receive upon the basis and upon the terms and conditions specified herein, in lieu of the shares of the Common Stock of the Company immediately theretofore purchasable hereunder, such shares of stock, securities or assets as may (by virtue of such consolidation, merger, sale, reorganization or reclassification) be issued or payable with respect to or in exchange for the number of shares of such Common Stock purchasable hereunder immediately before such consolidation, merger, sale, reorganization or reclassification. In any such case appropriate provision shall be made with respect to the rights and interests of the Holder of this Warrant to the end that the provisions hereof shall thereafter be applicable as nearly as may be, in relation to any shares of stock, securities or assets thereafter deliverable upon the exercise of this Warrant.

8.     Notice of Dissolution or Liquidation. In case of any distribution of the assets of the Company in dissolution or liquidation (except under circumstances when the foregoing Section 7 shall be applicable), the Company shall give notice thereof to the Holder hereof and shall make no distribution to shareholders until the expiration of five (5) days from the date of mailing of the aforesaid notice and, in any case, the Holder hereof may exercise this Warrant prior to the expiration date hereof within five (5) days from the date of the giving of such notice, and all rights herein granted not so exercised within such fifteen-day period shall thereafter become null and void.

9.     Notice of Extraordinary Dividends. If the Board of Directors of the Company shall declare any dividend or other distribution on its Common Stock except out of earned surplus or by way of a stock dividend payable in shares of its Common Stock, the Company shall mail notice thereof to the Holder hereof not less than five (5) days prior to the record date fixed for determining shareholders entitled to participate in such dividend or other distribution, and the Holder hereof shall not participate in such dividend or other distribution unless this Warrant is exercised prior to such record date.

10.     Fractional Shares. Fractional shares shall not be issued upon the exercise of this Warrant but in any case where the Holder would, except for the provisions of this Section 10, be entitled under the terms hereof to receive a fractional share upon the complete exercise of this Warrant, the Company shall, upon the exercise of this Warrant for the largest number of whole shares then called for, pay a sum in cash equal to the excess of the value of such fractional share (determined in such reasonable manner as may be prescribed in good faith by the Board of Directors of the Company) over the Warrant Price for such fractional share.

11.     Notices. Any notice or other document required or permitted to be given or delivered to the Holder shall be delivered by hand, by certified or registered mail, by courier or express delivery service, by facsimile or by e-mail to the Holder at 700 12^th Street, N.W., Suite 800, Washington, D.C. 20005 (facsimile: 202 ###-###-####) or to such other address as shall have been furnished to the Company in writing by the Holder. Any notice or other document required or permitted to be given or delivered to the Company shall be delivered by hand, by certified or registered mail, by courier or express delivery service, by facsimile or by e-mail the Company at 2200 Renaissance Boulevard, Suite 150, King of Prussia, Pennsylvania 1940 (facsimile: 610 ###-###-####) or to such other address as shall have been furnished in writing to the Holder by the Company. Any notice so addressed and delivered shall be deemed to be given when delivered.

12.     No Rights as Stockholder; Limitation of Liability. This Warrant shall not entitle the Holder to any of the rights of a stockholder of the Company. No provision hereof, in the absence of affirmative action by the Holder to purchase shares of Common Stock, and no mere enumeration herein of the rights or privileges of the Holder, shall give rise to any liability of the Holder for the Warrant Price hereunder or as a stockholder of the Company, whether such liability is asserted by the Company or by creditors of the Company.

13.     Miscellaneous. This Warrant shall be governed by, and construed and enforced in accordance with, the laws of the State of Delaware, without giving effect to its conflict of laws principles. The Holder and the Company consent to and agree to submit to the exclusive jurisdiction of the courts of the State of Delaware, state and federal, with respect to actions and proceedings relating to or arising out of this Warrant. This Warrant and any provision hereof may be changed, waived, discharged or terminated only by an instrument in writing signed by the party (or any predecessor in interest thereof) against which enforcement of the same is sought. The headings in this Warrant are for purposes of reference only and shall not affect the meaning or construction of any of the provisions hereof.

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

FORM OF NOTICE OF EXERCISE

[To be signed only upon exercise of the Warrant]

TO BE EXECUTED BY THE REGISTERED HOLDER

TO EXERCISE THE WITHIN WARRANT

The undersigned hereby exercises the right to purchase _________ shares of Common Stock which the undersigned is entitled to purchase by the terms of the within Warrant according to the conditions thereof, and herewith makes payment of the Warrant Price of such shares in full. All shares to be issued pursuant hereto shall be issued in the name of, and the initial address of such person to be entered on the books of the Company shall be:

The shares are to be issued in certificates of the following denominations:

FORM OF ASSIGNMENT

(ENTIRE)

[To be signed only upon transfer of entire Warrant]

TO BE EXECUTED BY THE REGISTERED HOLDER

TO TRANSFER THE WITHIN WARRANT

FOR VALUE RECEIVED ___________________________ hereby sells, assigns and transfers unto _______________________________ all rights of the undersigned under and pursuant to the within Warrant, and the undersigned does hereby irrevocably constitute and appoint _______________________________ Attorney to transfer the said Warrant on the books of the Company, with full power of substitution.

NOTICE

The signature to the foregoing Assignment must correspond to the name as written upon the face of the within Warrant in every particular, without alteration or enlargement or any change whatsoever.

FORM OF ASSIGNMENT

(PARTIAL)

[To be signed only upon partial transfer of Warrant]

TO BE EXECUTED BY THE REGISTERED HOLDER

TO TRANSFER THE WITHIN WARRANT

FOR VALUE RECEIVED _________________________ hereby sells, assigns and transfers unto _______________________________ (i) the rights of the undersigned to purchase _____ shares of Common Stock under and pursuant to the within Warrant, and (ii) on a non-exclusive basis, all other rights of the undersigned under and pursuant to the within Warrant, it being understood that the undersigned shall retain, severally (and not jointly) with the transferee(s) named herein, all rights assigned on such non-exclusive basis. The undersigned does hereby irrevocably constitute and appoint __________________________ Attorney to transfer the said Warrant on the books of the Company, with full power of substitution.

NOTICE

The signature to the foregoing Assignment must correspond to the name as written upon the face of the within Warrant in every particular, without alteration or enlargement or any change whatsoever.