Form of Assumed Warrant

Exhibit 4.1

FORM OF WARRANT

THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 AND MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN THE ABSENCE OF A REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO THE SECURITIES UNDER SUCH ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED.

No. _____

WARRANT TO PURCHASE COMMON STOCK

of

IMMUNOGENX, INC.

This certifies that, for value received, _______ or registered assigns (“Holder”) is entitled, subject to the terms set forth below, to purchase from Immunogenx, Inc. (the “Company”), a Delaware corporation, _______ shares of common stock, par value $0.0001 per share, of the Company, and any capital stock into which such Common Stock shall have been converted, exchanged, or reclassified following the date hereof (the “Common Stock”), beginning on the date hereof (the “Warrant Issue Date”), upon surrender hereof, at the principal office of the Company referred to below, with the subscription form attached hereto duly executed, and simultaneous payment therefor in lawful money of the United States or otherwise as hereinafter provided, at the Exercise Price as set forth in Section 2 below. The number, character and Exercise Price of such shares of Common Stock are subject to adjustment as provided below. The term “Warrant” as used herein shall include this Warrant, and any warrants delivered in substitution or exchange therefor as provided herein.

This Warrant has been issued pursuant to the terms of the Credit Agreement, dated as of even date herewith (the “Credit Agreement”), between the Company and the Holder

1. Term of Warrant. Subject to the terms and conditions set forth herein, this Warrant shall be exercisable, in whole or in part, during the term commencing on the Warrant Issue Date and ending at 5:00 p.m., Pacific Time, on _______ (the “Exercise Period”), and shall be void thereafter. The Company shall give the Holder written notice of the expiration of the Exercise Period not less than 10 days but not more than 30 days prior to the end of the Exercise Period.

2. Exercise Price. The Exercise Price at which this Warrant may be exercised shall be $____ per share of Common Stock, as adjusted from time to time pursuant to Section 11 hereof.

3. Exercise of Warrant.

3.1            Exercise. The purchase rights represented by this Warrant are exercisable by the Holder in whole or in part, at any time, or from time to time, during the Exercise Period, by the surrender of this Warrant and the Notice of Exercise annexed hereto duly completed and executed on behalf of the Holder, at the office of the Company (or such other office or agency of the Company as it may designate by notice in writing to the Holder at the address of the Holder appearing on the books of the Company), upon payment (i) in cash or by check acceptable to the Company, (ii) by cancellation by the Holder of indebtedness of the Company to the Holder, or (iii) by a combination of (i) and (ii), of the purchase price of the shares to be purchased.

This Warrant shall be deemed to have been exercised immediately prior to the close of business on the date of its surrender for exercise as provided above, and the person entitled to receive the shares of Common Stock issuable upon such exercise shall be treated for all purposes as the holder of record of such shares as of the close of business on such date. As promptly as practicable on or after such date and in any event within ten (10) days thereafter, the Company at its expense shall issue and deliver to the person or persons entitled to receive the same a certificate or certificates for the number of shares issuable upon such exercise. In the event that this Warrant is exercised in part, the Company at its expense will execute and deliver a new Warrant of like tenor exercisable for the number of shares for which this Warrant may then be exercised.

3.2            No Fractional Shares or Scrip. No fractional shares or scrip representing fractional shares shall be issued upon the exercise of this Warrant. In lieu of any fractional share to which the Holder would otherwise be entitled, the Company shall make a cash payment equal to the Exercise Price multiplied by such fraction.

3.3            Rights of Stockholders. Subject to Section 11 of this Warrant, the Holder shall not be entitled to vote or receive dividends or be deemed the holder of Common Stock or any other securities of the Company that may at any time be issuable on the exercise hereof for any purpose, nor shall anything contained herein be construed to confer upon the Holder, as such, any of the rights of a stockholder of the Company or any right to vote for the election of directors or upon any matter submitted to stockholders at any meeting thereof, or to give or withhold consent to any corporate action (whether upon any recapitalization, issuance of stock, reclassification of stock, change of par value, or change of stock to no par value, consolidation, merger, conveyance, or otherwise) or to receive notice of meetings, or to receive dividends or subscription rights or otherwise until the Warrant shall have been exercised and the shares of Common Stock purchasable upon the exercise hereof shall have been issued, as provided herein.

3.4            Transferability and Nonnegotiability of Warrant. This Warrant may not be transferred or assigned in whole or in part without compliance with all applicable federal and state securities laws by the transferor and the transferee (including the delivery of investment representation letters and legal opinions reasonably satisfactory to the Company, if such are requested by the Company). Subject to the provisions of this Warrant with respect to compliance with the Securities Act of 1933, as amended (the “Act”), title to this Warrant may be transferred by endorsement (by the Holder executing the Assignment Form annexed hereto) and delivery in the same manner as a negotiable instrument transferable by endorsement and delivery.

4. Compliance with Securities Laws. The Holder of this Warrant, by acceptance hereof, acknowledges that this Warrant and the shares of Common Stock or Common Stock to be issued upon exercise hereof or conversion thereof are being acquired solely for the Holder’s own account and not as a nominee for any other party, and for investment, and that the Holder will not offer, sell, or otherwise dispose of this Warrant or any shares of Common Stock or Common Stock to be issued upon exercise hereof or conversion thereof except under circumstances that will not result in a violation of the Act or any state securities laws. Upon exercise of this Warrant, the Holder shall, if requested by the Company, confirm in writing, in a form satisfactory to the Company, that the shares of Common Stock or Common Stock so purchased are being acquired solely for the Holder’s own account and not as a nominee for any other party, for investment, and not with a view toward distribution or resale.

This Warrant and all shares of Common Stock or Common Stock issued upon exercise hereof or conversion thereof shall be stamped or imprinted with a legend in substantially the following form (in addition to any legend required by state securities laws):

THE SECURITIES REPRESENTED HEREBY HAVE BEEN ACQUIRED FOR INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933. SUCH SECURITIES AND ANY SECURITIES OR SHARES ISSUED HEREUNDER OR THEREUNDER MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM UNDER SAID ACT.

5. Reservation of Stock. The Company covenants that during the Term this Warrant is exercisable, the Company will reserve from its authorized and unissued Common Stock a sufficient number of shares to provide for the issuance of Common Stock upon the exercise of this Warrant (and shares of its Common Stock for issuance on conversion of such Common Stock) and, from time to time, will take all steps necessary to amend its Certificate of Incorporation (the “Certificate”) to provide sufficient reserves of shares of Common Stock issuable upon exercise of the Warrant (and shares of its Common Stock for issuance on Conversion of such Common Stock). The Company further covenants that all shares that may be issued upon the exercise of rights represented by this Warrant, upon exercise of the rights represented by this Warrant and payment of the Exercise Price, all as set forth herein, will be free from all taxes, liens, and charges in respect of the issue thereof (other than taxes in respect of any transfer occurring contemporaneously or otherwise specified herein). The Company agrees that its issuance of this Warrant shall constitute full authority to its officers who are charged with the duty of executing stock certificates to execute and issue the necessary certificates for shares of Common Stock upon the exercise of this Warrant.

6. Notices. In the event:

(a)            that the Company shall take a record of the holders of its Common Stock (or other capital stock or securities at the time issuable upon exercise of the Warrant) for the purpose of entitling or enabling them to receive any dividend or other distribution, to vote at a meeting (or by written consent), to receive any right to subscribe for or purchase any shares of capital stock of any class or any other securities, or to receive any other right or security; or

(b)            of any capital reorganization of the Company, any reclassification of the capital stock of the Company, any consolidation or merger of the Company with or into another person or entity, or sale, transfer or conveyance of all or substantially all of the Company’s assets to another person or entity; or

(c)            of the voluntary or involuntary dissolution, liquidation, or winding-up of the Company;

then, and in each such case, the Company shall send or cause to be sent to the Holder at least twenty (20) days prior to the applicable record date or the applicable expected effective date, as the case may be, for the event, a written notice specifying, as the case may be, (A) the record date for such dividend, distribution, meeting or consent, or other right or action, and a description of such dividend, distribution, or other right or action to be taken at such meeting or by written consent, or (B) the effective date on which such reorganization, reclassification, consolidation, merger, sale, dissolution, liquidation, or winding-up is proposed to take place, and the date, if any is to be fixed, as of which the books of the Company shall close or a record shall be taken with respect to which the holders of record of Common Stock (or such other capital stock or securities at the time issuable upon exercise of the Warrant) shall be entitled to exchange their shares of Common Stock (or such other capital stock or securities) for securities or other property deliverable upon such reorganization, reclassification, consolidation, merger, sale, dissolution, liquidation, or winding-up, and the amount per share and character of such exchange applicable to the Warrant and the securities issuable hereunder.

7. Certificate of Adjustment. Whenever the Exercise Price or number of shares purchasable hereunder shall be adjusted pursuant to Section 11 hereof, the Company shall issue a certificate signed by its Chief Financial Officer setting forth, in reasonable detail, the event requiring the adjustment, the amount of the adjustment, the method by which such adjustment was calculated and the Exercise Price and number of shares purchasable hereunder after giving effect to such adjustment, and shall cause a copy of such certificate to be mailed (by first class mail, postage prepaid) to the Holder of this Warrant.

8. Replacement on Loss. Upon receipt of evidence reasonably satisfactory to the Company of the loss, theft, destruction, or mutilation of this Warrant and upon delivery of an indemnity reasonably satisfactory to it (it being understood that a written indemnification agreement or affidavit of loss of the Holder shall be a sufficient indemnity) and, in case of mutilation, upon surrender of such Warrant for cancellation to the Company, the Company at its own expense shall execute and deliver to the Holder, in lieu hereof, a new Warrant of like tenor and exercisable for an equivalent number and type of securities as the Warrant so lost, stolen, mutilated, or destroyed; provided, that, in the case of mutilation, no indemnity shall be required if this Warrant in identifiable form is surrendered to the Company for cancellation.

9. Purchase Rights. In addition to any adjustments pursuant to Section 11, if at any time the Company grants, issues, or sells any shares of Common Stock, options, convertible securities, or rights to purchase stock, warrants, securities, or other property pro rata to the record holders of Common Stock (the “Purchase Rights”), then the Holder shall be entitled to acquire, upon the terms applicable to such Purchase Rights, the aggregate Purchase Rights which the Holder would have acquired if the Holder had held the number of shares acquirable upon complete exercise of this Warrant immediately before the date on which a record is taken for the grant, issuance, or sale of such Purchase Rights, or, if no such record is taken, the date as of which the record holders of Common Stock are to be determined for the grant, issue, or sale of such Purchase Rights. Anything herein to the contrary notwithstanding, the Holder shall not be entitled to the Purchase Rights granted herein with respect to any issuance or sale by the Company after the Warrant Issue Date of: (a) shares of Common Stock issued upon the exercise of this Warrant; (b) shares of Common Stock (as such number of shares is equitably adjusted for subsequent stock splits, stock combinations, stock dividends, and recapitalizations) issued directly or upon the exercise of options to directors, officers, employees, or consultants of the Company in connection with their service as directors of the Company, their employment by the Company, or their retention as consultants by the Company, in each case authorized by the Board and issued pursuant to the Company’s equity incentive plan (including all such shares of Common Stock and options outstanding prior to the Warrant Issue Date); or (c) shares of Common Stock issued upon the conversion or exercise of Options (other than Options covered by clause (b) above) or convertible securities issued prior to the Warrant Issue Date, provided that such securities are not amended after the date hereof to increase the number of shares of Common Stock issuable thereunder or to lower the exercise or conversion price thereof.

10. [Intentionally Omitted.]

11. Adjustments. In order to prevent dilution of the purchase rights granted under this Warrant, the number of shares purchasable hereunder are subject to adjustment from time to time as follows:

11.1            Reorganization, Merger, Consolidation, Sale of Assets, Reclassification. If at any time, while this Warrant, or any portion thereof, is outstanding and unexpired there shall be (i) a reorganization (other than a combination, reclassification, exchange or subdivision of shares otherwise provided for herein), (ii) a merger or consolidation of the Company with or into another entity in which the Company is not the surviving entity, or a reverse triangular merger in which the Company is the surviving entity but the shares of the Company’s capital stock outstanding immediately prior to the merger are converted by virtue of the merger into other property, whether in the form of securities, cash, or otherwise, (iii) a sale or transfer of the Company’s properties and assets as, or substantially as, an entirety to any other person, (iv) reclassification of the capital stock of the Company, or (v) other similar transaction which entitles the holders of Common Stock to receive (either directly or upon subsequent liquidation) stock, securities, or assets with respect to or in exchange for Common Stock, then, as a part of such reorganization, merger, consolidation, sale or transfer, reclassification, or other transaction, lawful provision shall be made so that in lieu of or in addition to (as the case may be) the number of shares of Common Stock then exercisable under this Warrant, the Holder shall thereafter be entitled to receive upon exercise of this Warrant, during the period specified herein and upon payment of the Exercise Price then in effect, the number of shares of stock or other securities or property of the successor entity resulting from such reorganization, merger, consolidation, sale or transfer, reclassification, or other transaction which a holder of the shares deliverable upon exercise of this Warrant would have been entitled to receive in such reorganization, consolidation, merger, sale or transfer if this Warrant had been exercised immediately before such reorganization, merger, consolidation, sale or transfer, reclassification, or other transaction.

The foregoing provisions of this Section 11.1 shall similarly apply to successive reorganizations, consolidations, mergers, sales and transfers, reclassifications, and other similar transactions and to the stock or securities of any other corporation which are at the time receivable upon the exercise of this Warrant. If the per share consideration payable to the Holder for shares in connection with any such transaction is in a form other than cash or marketable securities, then the value of such consideration shall be determined in good faith by the Company’s Board of Directors and in form and substance reasonably satisfactory to the Holder. In all events, appropriate adjustment (as determined in good faith by the Company’s Board of Directors and reasonably satisfactory to the Holder) shall be made in the application of the provisions of this Warrant with respect to the rights and interests of the Holder after the transaction, to the end that the provisions of this Warrant shall be applicable after that event, as near as reasonably may be, in relation to any shares or other property deliverable after that event upon exercise of this Warrant.

11.2            Split, Subdivision or Combination of Shares. If the Company at any time while this Warrant, or any portion thereof, remains outstanding and unexpired shall split, subdivide or combine the securities as to which purchase rights under this Warrant exist, into a different number of securities of the same class, the Exercise Price for such securities shall be proportionately decreased in the case of a split or subdivision or proportionately increased in the case of a combination. Any adjustment under this Section 11.2 shall become effective at the close of business on the date the subdivision, or combination becomes effective.

11.3            Adjustments for Dividends in Stock or Other Securities or Property. If while this Warrant, or any portion hereof, remains outstanding and unexpired the holders of the securities as to which purchase rights under this Warrant exist at the time shall have received, or, on or after the record date fixed for the determination of eligible Stockholders, shall have become entitled to receive, without payment therefor, other or additional stock or other securities or property (other than cash) of the Company by way of dividend, then and in each case, this Warrant shall represent the right to acquire, in addition to the number of shares of the security receivable upon exercise of this Warrant, and without payment of any additional consideration therefor, the amount of such other or additional stock or other securities or property (other than cash) of the Company which such holder would hold on the date of such exercise had it been the holder of record of the security receivable upon exercise of this Warrant on the date hereof and had thereafter, during the period from the date hereof to and including the date of such exercise, retained such shares and/or all other additional stock available by it as aforesaid during such period, giving effect to all adjustments called for during such period by the provisions of this Section 11. Any adjustment under this Section 11.3 shall become effective at the close of business on the date the dividend becomes effective.

11.4            Certain Events. If any event of the type contemplated by the provisions of this Section 11 but not expressly provided for by such provisions (including, without limitation, the granting of stock appreciation rights, phantom stock rights, or other rights with equity features) occurs, then the Company’s Board of Directors shall make an appropriate adjustment in the number of securities issuable upon exercise of this Warrant so as to protect the rights of the Holder in a manner consistent with the provisions of this Section 11; provided, that no such adjustment pursuant to this Section 11.5 shall decrease the number of securities issuable as otherwise determined pursuant to this Section 11.

11.5            Certificate as to Adjustments. Upon the occurrence of each adjustment or readjustment pursuant to this Section 11, the Company at its expense shall promptly compute such adjustment or readjustment in accordance with the terms hereof and furnish to each holder of this Warrant a certificate setting forth such adjustment or readjustment and showing in detail the facts upon which such adjustment or readjustment is based. The Company shall, upon the written request, at any time, of any such holder, furnish or cause to be furnished to such holder a like certificate setting forth: (i) such adjustments and readjustments; (ii) the Exercise Price at the time in effect; and (iii) the number of shares and the amount, if any, of other property which at the time would be received upon the exercise of the Warrant.

12. No Impairment. The Company will not, by any voluntary action, avoid or seek to avoid the observance or performance of any of the terms to be observed or performed hereunder by the Company, but will at all times in good faith assist in the carrying out of all the provisions of this Section 11 and in the taking of all such action as may be necessary or appropriate in order to protect the rights of the holders of this Warrant against impairment.

13. Miscellaneous.

13.1            Choice of Law. This Agreement shall be governed by and construed under the laws of the State of Delaware, irrespective of such state's conflicts of law principles.

13.2            Counterparts. This Agreement may be executed in two or more counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. This Agreement shall not be effective until the execution and delivery between each of the parties of at least one set of counterparts. The parties authorize each other to detach and combine original signature pages and consolidate them into a single identical original. Any one of such completely executed counterparts shall be sufficient proof of this Agreement.

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IN WITNESS WHEREOF, Immunogenx, Inc. has caused this Warrant to be executed by its officers thereunto duly authorized.

Dated:_

NOTICE OF EXERCISE

To:

(1)      The undersigned hereby elects to purchase                   shares of Common Stock of                   , pursuant to the terms of the attached Warrant, and tenders herewith payment of the purchase price for such shares in full.

(2)            In exercising this Warrant, the undersigned hereby confirms and acknowledges that the shares of Common Stock or the Common Stock to be issued upon conversion thereof are being acquired solely for the account of the undersigned and not as a nominee for any other party, and for investment, and that the undersigned will not offer, sell, or otherwise dispose of any such shares of Common Stock or Common Stock except under circumstances that will not result in a violation of the Securities Act of 1933, as amended, or any state securities laws.

(3)            Please issue a certificate or certificates representing said shares of Common Stock in the name of the undersigned or in such other name as is specified below:

(4)            Please issue a new Warrant for the unexercised portion of the attached Warrant in the name of the undersigned or in such other name as is specified below:

ASSIGNMENT FORM

FOR VALUE RECEIVED, the undersigned registered owner of this Warrant hereby sells, assigns and transfers unto the Assignee named below all of the rights of the undersigned under the within Warrant, with respect to the number of shares of Common Stock (or Common Stock) set forth below:

and does hereby irrevocably constitute and appoint                          Attorney to make such transfer on the books of                      maintained for the purpose, with full power of substitution in the premises.

The undersigned also represents that, by assignment hereof, the Assignee acknowledges that this Warrant and the shares of stock to be issued upon exercise hereof or conversion thereof are being acquired for investment and that the Assignee will not offer, sell or otherwise dispose of this Warrant or any shares of stock to be issued upon exercise hereof or conversion thereof except under circumstances which will not result in a violation of the Securities Act of 1933, as amended, or any state securities laws. Further, the Assignee has acknowledged that upon exercise of this Warrant, the Assignee shall, if requested by the Company, confirm in writing, in a form satisfactory to the Company, that the shares of stock so purchased are being acquired for investment and not with a view toward distribution or resale.

DATED: