a5571729ex4_3.htm


    Exhibit
      4.3

    
       

      Form
        of
        Investor Warrant Agreement

       

      WARRANT
        AGREEMENT

       

      THIS
        WARRANT AGREEMENT (the “Agreement”) is dated _______ __, 2008, between
        Opexa Therapeutics, Inc., a Delaware corporation (the “Company”) and Continental
        Stock Transfer & Trust Company, acting as warrant agent (the “Warrant
        Agent”).

       

      WHEREAS,
        the Company proposes to issue warrants (collectively with any Additional
        Warrants, the “Series E Warrants”) to acquire up to
[5,625,000] shares, subject to adjustment as provided
        herein, of common stock, $ .50 par value (“Common Stock”), of the Company
        (collectively, the “Warrant Shares”);

       

      WHEREAS,
        each Series E Warrant shall represent the right to purchase from the
        Company, at an initial price of $______ per share [125% of price of
        share of common stock offered to public] (the “Exercise Price”),
        the number of shares specified on the certificates evidencing
        the  Series E Warrants (the “Warrant Certificates”); and

       

      WHEREAS,
        Continental Stock Transfer & Trust Company is willing to serve as the
        Warrant Agent in connection with the issuance of Warrant Certificates and
        the
        other matters as provided herein.

       

      NOW,
        THEREFORE, in consideration of the foregoing and for the purpose of
        defining the terms and provisions of the Series E Warrants and the
        respective rights and obligations thereunder of the Company, the Warrant
        Agent
        and the record holders from time to time of the Series E Warrants (the
“Holders”), the parties hereby agree as follows:

       

      1.  Definitions.  For
        the purposes hereof, the following terms shall have the following
        meanings:

       

      “Business
        Day” means any day except Saturday, Sunday and any day which shall be a federal
        legal holiday in the United States or a day on which banking institutions
        in The
        City of New York are authorized or required by law or other government action
        to
        close.

       

      “Date
        of
        Exercise” means the date on which the Holder shall have delivered to the Company
        (i) a Warrant Certificate, (ii) the Form of Election to Purchase
        attached thereto (with the Warrant Shares Exercise Log attached to it),
        appropriately completed and duly signed, and (iii) in the case of a Cash
        Exercise, payment of the Exercise Price in accordance with Section 9 for
        the
        number of Warrant Shares so indicated by the Holder to be
        purchased.

       

      “Exchange
        Act” means the Securities Exchange Act of 1934, as amended, and the rules and
        regulations of the Securities and Exchange Commission promulgated
        thereunder.

       

      “Expiration
        Date” means the date five years after the Initial Issuance Date.

       

      “Initial
        Issuance Date” means _________ __, 2008.

       

      
        
          
          

        

        
          
          

          
            

          

        

        
          
          

        

      

       

      “Market
        Price” of a share of Common Stock on any date shall mean, (i) if the shares
        of Common Stock are traded on the Nasdaq Global Market or Nasdaq Capital
        Market,
        the last bid price reported on that date; (ii) if the shares of Common
        Stock are no longer quoted on Nasdaq and are listed on any other national
        securities exchange, the last sale price of the Common Stock reported by
        such
        exchange on that date; (iii) if the shares of Common Stock are not quoted
        on a
        any such market or listed on any such exchange and the shares of Common Stock
        are traded in the over-the-counter market, the last price reported on such
        day
        by the OTC Bulletin Board; (iv) if the shares of Common Stock are not
        quoted on a any such market, listed on any such exchange or quoted on the
        OTC
        Bulletin Board, then the last price quoted on such day in the over-the-counter
        market as reported by the National Quotation Bureau Incorporated (or any
        similar
        organization or agency succeeding its functions of reporting prices); or
        (v) if none of clauses (i)-(iv) are applicable, then as determined, in
        good faith, by the Board of Directors of the Company.

       

      “Person”
        means a corporation, association, partnership, limited liability corporation,
        organization, business, individual, government or political subdivision thereof
        or governmental agency.

       

      “Trading
        Day” means (i) a day on which the shares of Common Stock are traded on the
        Nasdaq Global Market, Nasdaq Capital Market, New York Stock Exchange or American
        Stock Exchange on which the shares of Common Stock are then listed or quoted,
        or
        (ii) if the shares of Common Stock are not listed on a any such exchange or
        market, a day on which the shares of Common Stock are traded in the
        over-the-counter market, as reported by the OTC Bulletin Board, or (iii) if
        the shares of Common Stock are not quoted on the OTC Bulletin Board, a day
        on
        which the shares of Common Stock are quoted in the over-the-counter market
        as
        reported by the National Quotation Bureau Incorporated (or any similar
        organization or agency succeeding its functions of reporting prices); provided,
        that in the event that the shares of Common Stock are not listed or quoted
        as
        set forth in clause (i), (ii) or (iii) hereof, then Trading Day shall mean
        a Business Day.

       

      2.  Form
        of
        Warrant Certificates.

       

      (a)  Form.  The
        Warrant Certificates shall be issued in registered form only as definitive
        Warrant Certificates and shall be substantially in the form attached hereto
        as
        Exhibit A, shall be dated the date of issuance thereof (whether upon
        initial issuance, register of transfer, exchange or replacement) and shall
        bear
        such legends and endorsements typed, stamped, printed, lithographed or engraved
        thereon as the Company may deem appropriate and as are not inconsistent with
        the
        provisions of this Agreement. Warrant Certificates evidencing Series E Warrants
        to purchase the number of shares of Common Stock specified on each Warrant
        Certificate shall be signed by, or bear the facsimile signature of, the Chairman
        of the Board, Chief Executive Officer, President, any Vice President, Treasurer
        or Secretary of the Company. In the event the person whose facsimile signature
        has been placed upon any Warrant Certificate shall have ceased to serve in
        the
        capacity in which such person signed the Warrant Certificate before such
        Warrant
        Certificate is issued, it may be issued with the same effect as if he or
        she had
        not ceased to be such at the date of issuance.

       

      
        
          
          

        

        
          2

          
            

          

        

        
          
          

        

      

       

      (b)  Effect
        of Countersignature.  Unless and until countersigned by the
        Warrant Agent pursuant to this Agreement, a Warrant Certificate shall be
        invalid
        and of no effect and may not be exercised by the holder thereof. Such signature
        by the Warrant Agent upon any Warrant Certificate executed by the Company
        shall
        be conclusive evidence that such Warrant Certificate has been duly issued
        under
        the terms of this Agreement.

       

      (c)  Warrant
        Register.  The Warrant Agent shall maintain books (the “Warrant
        Register”), for the registration of original issuance and the registration of
        transfer of Warrant Certificates. Upon the initial issuance of the Warrant
        Certificates, the Warrant Agent shall issue and register the Warrant
        Certificates in the names of the respective holders thereof in such
        denominations and otherwise in accordance with instructions delivered to
        the
        Warrant Agent by the Company. The Company and the Warrant Agent may deem
        and
        treat the registered Holder of each Warrant Certificate as the absolute owner
        of
        the Series E Warrants represented thereby for the purpose of any exercise
        thereof or any distribution to the Holder, and for all other purposes, absent
        actual notice to the contrary.

       

      (d)  Registration
        of Transfers.  The Warrant Agent shall register the transfer of
        any portion of a Warrant Certificate in the Warrant Register, upon surrender
        of
        the Warrant Certificate, with the Form of Assignment attached thereto duly
        completed and signed, to the Company at its address specified herein. Upon
        any
        such registration or transfer, a new Warrant Certificate substantially in
        the
        form attached hereto as Exhibit A (any such new Warrant Certificate, a “New
        Warrant Certificate”), evidencing the portion of the Warrant Certificate so
        transferred shall be issued to the transferee and a New Warrant Certificate
        evidencing the remaining portion of the Warrant Certificate not so transferred,
        if any, shall be issued to the transferring Holder. The delivery of the New
        Warrant Certificate by the Company to the transferee thereof shall be deemed
        to
        constitute acceptance by such transferee of all of the rights and obligations
        of
        a holder of a Warrant Certificate.

       

      3.  Term
        of
        Series E Warrants.  Subject to the terms of Section 4,
        Series E Warrants shall be exercisable by the registered Holder at any time
        and from time to time on or after the Initial Issuance Date to and including
        the
        Expiration Date. At 5:00 p.m., Houston time on the Expiration Date, any
        portion of a Series E Warrant not exercised prior thereto shall be and
        become void and of no value.

       

      4.  Exercise
        of Series E Warrants and Delivery of Warrant Shares.

       

      (a)  If
        an
        effective registration statement is then available for the issuance of the
        Warrant Shares and the exercise is permitted in the state of the residence
        of
        the registered Holder, a registered Holder may only exercise the Series E
        Warrants through a cash exercise (a “Cash Exercise”).  If an effective
        registration statement is not then available for the issuance of the Warrant
        Shares under the Federal securities laws or the state “blue sky” laws of the
        state of the residence of the registered Holder, then a registered Holder
        may
        exercise the Series E Warrants through either (i) through a cashless
        exercise (a “Cashless Exercise”) pursuant to Section 4(b) below or
        (ii) through a Cash Exercise after making customary representations
        requested by the Company regarding investment intent and accredited status
        and
        agreeing to customary transfer restrictions requested by the Company to ensure
        compliance by the Company with applicable securities laws.

       

      
        
          
          

        

        
          3

          
            

          

        

        
          
          

        

      

       

      (b)  The
        Holder
        shall effect a Cashless Exercise by surrendering Warrant Certificates to
        the
        Warrant Agent and noting on the Form of Election to Purchase that the Holder
        wishes to effect a Cashless Exercise, upon which the Company shall issue,
        or
        cause to be issued, to the Holder the number of Warrant Shares determined
        as
        follows:

       

      
        
          	 	
                  X

                	
                  =

                	
                  Y
                    x
                    (A-B)/A

                


        

         

        
          	 	 where:  
	 	
                  X

                	
                  =

                	
                  the
                    number of Warrant Shares to be issued to the Holder;

                
	 	
                  Y

                	
                  =

                	
                  the
                    number of Warrant Shares with respect to which the Warrant Certificates
                    are being exercised;

                
	 	
                  A

                	
                  =

                	
                  the
                    Market Price as of the Date of Exercise; and

                
	 	
                  B

                	
                  =

                	
                  the
                    Exercise Price.

                


        

         

      

      (c)  At
        such
        times, and upon such representations and agreements, if applicable, upon
        surrender of a Warrant Certificate and delivery of the Form of Election to
        Purchase (with the Warrant Shares Exercise Log attached) to the Warrant Agent
        at
        its address for notice set forth in Section 14, and, in the case of a Cash
        Exercise, upon payment of the Exercise Price multiplied by the number of
        Warrant
        Shares that the Holder intends to purchase thereunder (which must be a whole
        number) in accordance with Section 9 (the “Aggregate Exercise Price”), the
        Company shall promptly issue and deliver to the Holder a certificate for
        the
        Warrant Shares issuable upon such exercise. Any Person so designated by the
        Holder to receive Warrant Shares shall be deemed to have become holder of
        record
        of such Warrant Shares as of the Date of Exercise of the relevant Warrant
        Certificate. For so long as there is a then effective registration statement
        covering the issuance of the Warrant Shares or if a Holder effects a Cashless
        Exercise, the Warrant Shares shall be issued free of all restrictive legends,
        and the Company shall, upon request of the Holder, if available, use
        commercially reasonable efforts to deliver Warrant Shares hereunder
        electronically through the Depository Trust Corporation or another established
        clearing corporation performing similar functions. If there is not a then
        effective registration statement covering the issuance of the Warrant Shares
        and
        a Holder effects a Cash Exercise, the Warrant Shares shall be issued in
        certificated form and include customary legends regarding transfer restrictions
        deemed appropriate by the Company. If fewer than all Warrant Shares issuable
        upon exercise of the relevant Warrant Certificate are purchased on such Date
        of
        Exercise, then the Company will execute and deliver to the Holder or its
        assigns
        a New Warrant Certificate (dated the date thereof) evidencing the unexercised
        portion of the relevant Warrant Certificate.

       

      5.  Charges,
        Taxes and Expenses.  Issuance and delivery of certificates for
        Warrant Shares shall be made without charge to the Holder for any issue or
        transfer tax, or transfer agent fee in respect of the issuance of such
        certificates, all of which taxes shall be paid by the Company; provided,
        however, that the Company shall not be obligated to pay any tax which may
        be
        payable in respect of any transfer involved in the registration of any
        certificates for Warrant Shares or Series E Warrants in a name other than
        that of the Holder. The Holder shall be responsible for all other tax
        liabilities that may arise as a result of holding or transferring any Warrant
        Certificate or receiving Warrant Shares upon exercise thereof.

       

      
        
          
          

        

        
          4

          
            

          

        

        
          
          

        

      

       

      6.  Replacement
        of Warrant Certificate.  If any Warrant Certificate is mutilated,
        lost, stolen or destroyed, the Company shall issue or cause to be issued
        in
        exchange and substitution for and upon cancellation thereof, or in lieu of
        and
        substitution for such Warrant Certificate, a New Warrant Certificate, but
        only
        upon receipt of evidence reasonably satisfactory to the Company of such loss,
        theft or destruction and customary and reasonable indemnity, if requested.
        Applicants for a New Warrant Certificate under such circumstances shall also
        comply with such other reasonable regulations and procedures and pay such
        other
        reasonable third-party costs as the Company may prescribe.

       

      7.  Reservation
        of Warrant Shares.  The Company covenants that it will at all
        times reserve and keep available out of its authorized but unissued and
        otherwise unreserved Common Stock, solely for the purpose of enabling it
        to
        issue Warrant Shares upon exercise of all outstanding Series E Warrants as
        herein provided, the number of Warrant Shares which are then issuable and
        deliverable upon the exercise of all outstanding Series E Warrants (taking
        into account the adjustments and restrictions of Section 8). The Company
        covenants that all 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 and issued, and be fully paid
        and
        nonassessable.

       

      8.  Certain
        Adjustments.  The Exercise Price and number of Warrant Shares
        issuable upon exercise of each Series E Warrant then outstanding are
        subject to adjustment from time to time as set forth in this
        Section 8.

       

      (a)  Stock
        Dividends and Splits.  If the Company, (i) pays a stock
        dividend on its Common Stock, (ii) subdivides outstanding shares of Common
        Stock into a greater number of shares, or (iii) combines outstanding shares
        of Common Stock into a lesser number of shares, then in each such case the
        Exercise Price shall be multiplied by a fraction of which the numerator shall
        be
        the number of shares of Common Stock outstanding immediately before such
        event
        and of which the denominator shall be the number of shares of Common Stock
        outstanding immediately after such event. Any adjustment made pursuant to
        clause (i) of this paragraph shall become effective immediately after the
        record date for the determination of shareholders entitled to receive such
        dividend, and any adjustment pursuant to clause (ii) or (iii) of this
        paragraph shall become effective immediately after the effective date of
        such
        subdivision or combination.

       

      (b)  Extraordinary
        Transactions.  If, (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 in one or a series
        of
        related transactions, (iii) any tender offer or exchange offer by the
        Company is completed pursuant to which holders of Common Stock are permitted
        to
        tender or exchange their shares for other securities, cash or property, or
        (iv) the Company effects any reclassification of the Common Stock or any
        compulsory share exchange pursuant to which the Common Stock is effectively
        converted into or exchanged for other securities, cash or property (in any
        such
        case, an “Extraordinary Transaction”), then each Holder’s Series E Warrants will
        become the right thereafter to receive, upon exercise of his or her Series
        E
        Warrants, the same amount and kind of securities, cash or property as such
        Holder would have been entitled to receive upon the occurrence of such
        Extraordinary Transaction if it had been, immediately prior to such
        Extraordinary Transaction, the holder of the number of Warrant Shares then
        issuable upon exercise in full of the relevant Series E Warrant (the “Alternate
        Consideration”) in lieu of Common Stock. The aggregate Exercise Price for each
        Series E Warrant will not be affected by any such Extraordinary
        Transaction, but the Company shall apportion such aggregate Exercise Price
        among
        the Alternate Consideration in a reasonable manner reflecting the relative
        value
        of any different components of the Alternate Consideration. If holders of
        Common
        Stock are given any choice as to the securities, cash or property to be received
        in a Extraordinary Transaction, then each Holder, to the extent practicable,
        shall be given the same choice as to the Alternate Consideration it receives
        upon any exercise of his or her Series E Warrant following such Extraordinary
        Transaction. In addition, at the request of each Holder, upon surrender of
        such
        Holder’s Series E Warrant, any successor to the Company or surviving entity
        in such Extraordinary Transaction shall issue to such Holder a new warrant
        consistent with the foregoing provisions and evidencing the Holder’s right to
        purchase the Alternate Consideration for the aggregate Exercise Price upon
        exercise thereof. Each Series E Warrant (or any such replacement security)
        will
        be similarly adjusted upon any subsequent transaction analogous to a
        Extraordinary Transaction.

       

      
        
          
          

        

        
          5

          
            

          

        

        
          
          

        

      

       

      (c)  Number
        of Warrant Shares.  Simultaneously with any adjustment to the
        Exercise Price pursuant to paragraph (a) of this Section, the number of
        Warrant Shares that may be purchased upon exercise of each Series E Warrant
        shall be increased or decreased proportionately, as the case may be, so that
        after such adjustment the aggregate Exercise Price payable hereunder for
        the
        adjusted number of Warrant Shares shall be the same as the aggregate Exercise
        Price in effect immediately prior to such adjustment.

       

      (d)  Calculations.  All
        calculations under this Section 8 shall be made to the nearest cent or the
        nearest 1/100th of a share, as applicable.

       

      (e)  Notice
        of Adjustments.  Upon the occurrence of each adjustment pursuant
        to this Section 8, the Company at its expense will promptly calculate such
        adjustment in accordance with the terms of this Agreement and prepare a
        certificate setting forth such adjustment, including a statement of the adjusted
        Exercise Price and adjusted number of Warrant Shares or type of Alternate
        Consideration issuable upon exercise of each Series E Warrant (as
        applicable), describing the transactions giving rise to such adjustments
        and
        showing in detail the facts upon which such adjustment is based. The Company
        will promptly deliver to each Holder who makes a request in writing and to
        the
        Warrant Agent, a copy of each such certificate.

       

      (f)  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 (other than a dividend payable solely in shares of Common
        Stock) or (ii) authorizes the voluntary dissolution, liquidation or winding
        up of the affairs of the Company, then the Company shall deliver to each
        Holder
        a notice describing the material terms and conditions of such dividend,
        distribution or transaction. Notwithstanding anything to the contrary in
        this
        Section 8(f), the failure to deliver any notice under this
        Section 8(f) or any defect therein shall not affect the validity of the
        corporate action required to be described in such notice. Until the exercise
        of
        its, his or her Series E Warrant or any portion of such Series E
        Warrant, a Holder shall not have nor exercise any rights by virtue of ownership
        of a Series E Warrant as a shareholder of the Company (including without
        limitation the right to notification of shareholder meetings or the right
        to
        receive any notice or other communication concerning the business and affairs
        of
        the Company other than as provided in this Section 8(f)).

       

      
        
          
          

        

        
          6

          
            

          

        

        
          
          

        

      

       

      9.  Payment
        of Exercise Price.  The Holder shall pay the Aggregate Exercise
        Price by paying, in lawful money of the United States, in cash, certified
        check
        or bank draft payable to the order of the Company (or as otherwise agreed
        to by
        the Company) delivered to the Warrant Agent together with the Warrant
        Certificate and Form of Election to Purchase.

       

      10.  Company
        Call Right.  Notwithstanding any other provision contained in this
        Warrant Agreement to the contrary, in the event that the average closing
        bid
        prices per share of Common Stock, as quoted on the Nasdaq Global Market (or
        such
        other exchange or stock market on which the Common Stock may then be listed
        or
        quoted) over a period of 20 consecutive Trading Days, equals or exceeds
        200% of the Exercise Price (appropriately adjusted for any stock split, reverse
        stock split, stock dividend or other reclassification or combination of the
        Common Stock occurring after the date hereof), the Company, upon thirty
        (30) calendar days prior written notice (the “Notice Period”) given to the
        Holder within 10 Business Days of the end of such 20 consecutive Trading
        Day period, may call the Series E Warrants, in whole and not in part, at a
        redemption price equal to $0.01 per share of Common Stock then purchasable
        pursuant to the Series E Warrants called for redemption. The Holder shall
        have the right to exercise the Series E Warrants prior to the end of the
        Notice Period. As of the last day of the Notice Period, any Series E
        Warrants timely and validly called for redemption by the Company shall terminate
        and permanently cease to be exercisable and the Holders shall then be entitled
        only to receive the redemption price.

       

      Notwithstanding
        the ability of the
        Company to call the Series E Warrants for redemption, the Company agrees
        that the Series E Warrants underlying any warrant agreement issued to the
        underwriters and their designees and transferees in connection with the public
        offering in which the Series E Warrants were issued will not be subject to
        the call right and redemption set forth herein.

       

      11.  Holder
        not Deemed a Stockholder.  Except as otherwise specifically
        provided herein, the Holder, solely in such Person’s capacity as a Holder, shall
        not be entitled to vote or receive dividends or be deemed the holder of share
        capital of the Company for any purpose, nor shall anything contained in the
        Series E Warrants be construed to confer upon the Holder, solely in such
        Person’s capacity as a Holder, any of the rights of a stockholder of the Company
        or any right to vote, give or withhold consent to any corporate action (whether
        any reorganization, issue of stock, reclassification of stock, consolidation,
        merger, conveyance or otherwise), receive notice of meetings, receive dividends
        or subscription rights, or otherwise, prior to the issuance to the Holder
        of the
        Warrant Shares to which Person is then entitled to receive upon the due exercise
        of the Series E Warrants.

       

      
        
          
          

        

        
          7

          
            

          

        

        
          
          

        

      

       

      12.  No
        Fractional Shares.  No fractional shares will be issued in
        connection with any exercise of a Series E Warrant. In lieu of any
        fractional shares which would otherwise be issuable, the Company shall pay
        cash
        equal to the product of such fraction multiplied by the Market Price on the
        Date
        of Exercise.

       

      13.  Exchange
        Act Filings.  The Holder agrees and acknowledges that it shall
        have sole responsibility for making any applicable filings with the U.S.
        Securities and Exchange Commission pursuant to Sections 13 and 16 of the
        Exchange Act as a result of its acquisition of any Series E Warrant and the
        Warrant Shares and any future retention or transfer thereof.

       

      14.  Notices.  Any
        and all notices or other communications or deliveries hereunder (including
        without limitation any Exercise Notice) shall be in writing and shall be
        deemed
        given and effective on the earliest of (i) the date of transmission, if
        such notice or communication is delivered via facsimile at the facsimile
        number
        specified in this Section prior to 5:00 p.m. (Houston time) on a Trading
        Day, (ii) the next Trading Day after the date of transmission, if such
        notice or communication is delivered via facsimile at the facsimile number
        specified in this Section on a day that is not a Trading Day or later than
        5:00 p.m. (Houston time) on any Trading Day, (iii) the Trading Day
        following the date of mailing, if sent by nationally recognized overnight
        courier service, or (iv) upon actual receipt by the party to whom such
        notice is required to be given. The addresses for such communications shall
        be:

       

      if
        to the
        Company:

      


      Opexa
        Therapeutics, Inc.

      2635
        North Crescent Ridge
        Drive

      The
        Woodlands, Texas 77381

      Attn:
        Chief Financial
        Officer

      Facsimile
        No.: (281)
        872-8585

      


      if
        to the
        Warrant Agent:

      Continental
        Stock Transfer & Trust
        Company

      17
        Battery Place, 8th
        Floor

      New
        York, New York 10004

      Attention:
        Office of General
        Counsel

      


      if
        to the
        Holder:

      


      to
        the
        address or facsimile number appearing on the Warrant Register or such other
        address or facsimile number as the Holder may provide to the Company in
        accordance with this Section 14.

      


      
        
          
          

        

        
          8

          
            

          

        

        
          
          

        

      

       

      15.  Warrant
        Agent.

       

      (a)  The
        Company and the Warrant Agent hereby agree that the Warrant Agent will serve
        as
        an agent of the Company as set forth in this Agreement.

       

      (b)  The
        Warrant Agent shall not by any act hereunder be deemed to make any
        representation as to validity or authorization of the Series E Warrants or
        the Warrant Certificates (except as to its countersignature thereon) or of
        any
        securities or other property delivered upon exercise of any Series E
        Warrant, or as to the number or kind or amount of securities or other property
        deliverable upon exercise of any Series E Warrant or the correctness of the
        representations of the Company made in such certificates that the Warrant
        Agent
        receives.

       

      (c)  The
        Warrant Agent shall not have any duty to calculate or determine any required
        adjustments with respect to the Exercise Price or the kind and amount of
        securities or other property receivable by Holders upon the exercise of
        Series E Warrants, nor to determine the accuracy or correctness of any such
        calculation.

       

      (d)  The
        Warrant Agent shall not (i) be liable for any recital or statement of fact
        contained herein or in the Warrant Certificates or for any action taken,
        suffered or omitted by it in good faith in the belief that any Warrant
        Certificate or any other document or any signature is genuine or properly
        authorized, (ii) be responsible for any failure by the Company to comply
        with any of its obligations contained in this Agreement or in the Warrant
        Certificates, (iii) be liable for any act or omission in connection with
        this Agreement except for its own gross negligence or willful misconduct
        or
        (iv) have any responsibility to determine whether a transfer of a
        Series E Warrant complies with applicable securities laws.

       

      (e)  The
        Warrant Agent is hereby authorized to accept instructions with respect to
        the
        performance of its duties hereunder from the Chief Executive Officer, the
        President, any Vice President, the Treasurer, or the Secretary or any Assistant
        Secretary of the Company and to apply to any such officer for written
        instructions (which will then be promptly given) and the Warrant Agent shall
        not
        be liable for any action taken or suffered to be taken by it in good faith
        in
        accordance with the instructions of any such officer, except for its own
        gross
        negligence or willful misconduct, but in its discretion the Warrant Agent
        may in
        lieu thereof accept other evidence of such or may require such further or
        additional evidence as it may deem reasonable.

       

      (f)  The
        Warrant Agent may exercise any of the rights and powers hereby vested in
        it or
        perform any duty hereunder either itself or by or through its attorneys,
        agents
        or employees, provided reasonable care has been exercised in the selection
        and
        in the continued employment of any persons. The Warrant Agent shall not be
        under
        any obligation or duty to institute, appear in or defend any action, suit
        or
        legal proceeding in respect hereof, unless first indemnified to its
        satisfaction. The Warrant Agent shall promptly notify the Company in writing
        of
        any claim made or action, suit or proceeding instituted against or arising
        out
        of or in connection with this Agreement.

       

      
        
          
          

        

        
          9

          
            

          

        

        
          
          

        

      

       

      (g)  The
        Company will take such action as may reasonably be required by the Warrant
        Agent
        in order to enable it to carry out or perform its duties under this
        Agreement.

       

      (h)  The
        Warrant Agent shall act solely as agent of the Company hereunder. The Warrant
        Agent shall only be liable for the failure to perform such duties as are
        specifically set forth herein.

       

      (i)  The
        Warrant Agent may consult with legal counsel satisfactory to it (who may
        be
        legal counsel for the Company), and the Warrant Agent shall incur no liability
        or responsibility to the Company or to any Holder for any action taken, suffered
        or omitted by it in good faith in accordance with the opinion or advice of
        such
        counsel.

       

      (j)  The
        Company agrees to pay to the Warrant Agent compensation for all services
        rendered by the Warrant Agent hereunder as the Company and the Warrant Agent
        may
        agree from time to time, and to reimburse the Warrant Agent for reasonable
        expenses incurred in connection with the execution and administration of
        this
        Agreement (including the reasonable compensation and expenses of its counsel),
        and further agrees to indemnify the Warrant Agent for, and hold it harmless
        against, any loss, liability or expense incurred without gross negligence,
        bad
        faith or willful misconduct on its part, arising out of or in connection
        with
        the acceptance and administration of this Agreement.

       

      (k)  The
        Warrant Agent, and any shareholder, director, officer or employee of the
        Warrant
        Agent, may buy, sell or deal in any of the Series E Warrants or other
        securities of the Company or its Affiliates or become pecuniarily interested
        in
        transactions in which the Company or its Affiliates may be interested, or
        contract with or lend money to the Company or its Affiliates or otherwise
        act as
        fully and freely as though it were not the Warrant Agent under this Agreement.
        Nothing herein shall preclude the Warrant Agent from acting in any other
        capacity for the Company or for any other Person.

       

      (l)  No
        resignation or removal of the Warrant Agent and no appointment of a successor
        warrant agent shall become effective until the acceptance of appointment
        by the
        successor warrant agent as provided herein. The Warrant Agent may resign
        its
        duties and be discharged from all further duties and liability hereunder
        (except
        liability arising as a result of the Warrant Agent’s own gross negligence or
        willful misconduct) after giving written notice to the Company. The Company
        may
        remove the Warrant Agent upon written notice, and the Warrant Agent shall
        thereupon in like manner be discharged from all further duties and liabilities
        hereunder, except as aforesaid. The Warrant Agent shall, at the Company’s
        expense, cause to be mailed (by first class mail, postage prepaid) to each
        Holder of a Series E Warrant at such Holder’s last address as shown on the
        register of the Company maintained by the Warrant Agent a copy of said notice
        of
        resignation or notice of removal, as the case may be. Upon such resignation
        or
        removal, the Company shall appoint in writing a new warrant agent. If the
        Company fails to do so within a period of 30 days after it has been
        notified in writing of such resignation by the resigning Warrant Agent or
        after
        such removal, then the resigning Warrant Agent or the Holder of any
        Series E Warrant may apply to any court of competent jurisdiction for the
        appointment of a new warrant agent. After acceptance in writing of such
        appointment by the new warrant agent, it shall be vested with the same powers,
        rights, duties and responsibilities as if it had been originally named herein
        as
        the Warrant Agent. Not later than the effective date of any such appointment,
        the Company shall give notice thereof to the resigning or removed Warrant
        Agent.
        Failure to give any notice provided for in this Section 15(l), however, or
        any
        defect therein, shall not affect the legality or validity of the resignation
        of
        the Warrant Agent or the appointment of a new warrant agent, as the case
        may
        be.

       

      
        
          
          

        

        
          10

          
            

          

        

        
          
          

        

      

       

      (m)  Any
        corporation into which the Warrant Agent or any new warrant agent may be
        merged
        or any corporation resulting from any consolidation to which the Warrant
        Agent
        or any new warrant agent shall be a party or any corporation to which the
        Warrant Agent transfers substantially all of its corporate trust business
        shall
        be a successor Warrant Agent under this Agreement without any further act,
        provided that such corporation (i) would be eligible for appointment as
        successor to the Warrant Agent under the provisions of Section 15(l) or
        (ii) is a wholly owned subsidiary of the Warrant Agent. 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 each Holder in accordance
        with Section 14.

       

      16.  Miscellaneous.

       

      (a)  Successors
        and Assigns.  This Agreement shall be binding on and inure to the
        benefit of the Company, the Warrant Agent and the Holders, and their respective
        successors and assigns. Subject to the preceding sentence, nothing in this
        Agreement shall be construed to give to any Person other than the Company,
        the
        Warrant Agent and the Holders any legal or equitable right, remedy or cause
        of
        action under this Agreement.

       

      (b)  Amendments
        and Waivers.  The Company may, without the consent of the
        Holders, by supplemental agreement or otherwise, (i) make any changes or
        corrections in this Agreement that are required to cure any ambiguity or
        to
        correct or supplement any provision herein which may be defective or
        inconsistent with any other provision herein or (ii) add to the covenants
        and agreements of the Company for the benefit of the Holders, or surrender
        any
        rights or power reserved to or conferred upon the Company in this Agreement;
        provided that, in the case of (i) or (ii), such changes or corrections shall
        not
        adversely affect the interests of Holders of then outstanding Series E Warrants
        in any material respect. The Company may, with the consent, in writing or
        at a
        meeting, of the Holders of outstanding Series E Warrants exercisable for
        two-thirds of the Warrant Shares, amend in any way, by supplemental agreement
        or
        otherwise, this Agreement and/or all of the outstanding Warrant Certificates;
        provided, however, that no such amendment shall adversely affect any
        Series E Warrant differently than it affects all other Series E
        Warrants, unless the Holder thereof consents thereto. The Warrant Agent shall
        at
        the request of the Company, and without need of independent inquiry as to
        whether such supplemental agreement is permitted by the terms of this
        Section 16(b), join with the Company in the execution and delivery of any
        such supplemental agreements, but shall not be required to join in such
        execution and delivery for such supplemental agreement to become
        effective.

       

      
        
          
          

        

        
          11

          
            

          

        

        
          
          

        

      

       

      (c)  Choice
        of Law, etc.  All questions concerning the construction,
        validity, enforcement and interpretation of this Agreement shall be governed
        by
        and construed and enforced in accordance with the internal laws of the State
        of
        New York, without regard to the principles of conflicts of law thereof. Each
        party hereto hereby irrevocably waives, to the fullest extent permitted by
        applicable law, any and all right to trial by jury in any legal proceeding
        arising out of or relating to this Agreement or the transactions contemplated
        hereby. If either party shall commence an action or proceeding to enforce
        any
        provisions of this Agreement, then the prevailing party in such action or
        proceeding shall be reimbursed by the other party for its attorneys’ fees and
        other costs and expenses incurred with the investigation, preparation and
        prosecution of such action or proceeding.

       

      (d)  Interpretation.  The
        headings herein are for convenience only, do not constitute a part of this
        Agreement and shall not be deemed to limit or affect any of the provisions
        hereof.

       

      (e)  Severability.  In
        case any one or more of the provisions of this Agreement shall be invalid
        or
        unenforceable in any respect, the validity and enforceability of the remaining
        terms and provisions of this Agreement 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 Agreement.

       

      (f)  Additional
        Series E Warrants. The Company may from time to time issue additional
        warrants (the “Additional Warrants”) under this Warrant Agreement, without
        requiring the consent of any Holder, with the same terms as the warrants
        initially issued hereunder.

       

      [The
        remainder of this page has been left intentionally blank.]

       

      
        
          
          

        

        
          12

          
            

          

        

        
          
          

        

      

       

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

       

      
        


        
          	 	
                  OPEXA
                    THERAPEUTICS, INC.

                	 
	 	 	 	 
	 	 	 	 
	 	
                  By:

                	 	 
	 	
                  Name:

                	
                  David
                    B. McWilliams

                	 
	 	
                  Title:

                	
                  President

                	 


        

        


        


        


        


        


        
          	 	
                  CONTINENTAL
                    STOCK TRANSFER & TRUST COMPANY

                	 
	 	 	 	 
	 	 	 	 
	 	
                  By:

                	 	 
	 	
                  Name:

                	 	 
	 	
                  Title:

                	 	 


        

         

        
          
            
            

          

          
            
              Signature
                page to Warrant Agreement

            

            
              

            

          

          
            
            

          

        

      

       

      Exhibit
        A

       

      EXERCISABLE
        ON OR AFTER ________ __, 2008

      AND
        ON OR
        BEFORE _______ __, 2013

       

      
        
          	
                  No.
                    ____________

                	 	
                  Series E
                    Warrant to Purchase ___________
                    Shares

                


        

      

       

      Series E
        Warrant Certificate

       

      WARRANTS
        TO ACQUIRE COMMON STOCK OF OPEXA THERAPEUTICS, INC.

       

      This
        Series E Warrant Certificate certifies that,
        _________________________________, or registered assigns, is the registered
        holder of a Series E Warrant (the “Warrant”) to acquire from Opexa
        Therapeutics, Inc., a Delaware corporation (the “Company”), the number of fully
        paid and non-assessable shares of Common Stock, $.50 par value, of the Company
        (the “Common Stock”) specified above for consideration equal to $ _____________
        (the “Exercise Price”) per share of Common Stock. The Series E Warrant
        evidenced by this Series E Warrant Certificate shall not be exercisable
        after and shall terminate and become void as of 5:00 P.M., Houston time,
        on
        ________ ___, 2013 (the “Expiration Date”).

       

      The
        Series E Warrant evidenced by this Series E Warrant Certificate is
        part of a duly authorized issue of warrants expiring on the Expiration Date
        entitling the Holder hereof to receive shares of Common Stock, and is issued
        or
        to be issued pursuant to a Warrant Agreement dated _______ _____, 2008 (the
“Warrant Agreement”), duly executed and delivered by the Company to Continental
        Stock Transfer & Trust Company, as warrant agent (the “Warrant Agent”,
        which term includes any successor Warrant Agent under the Warrant Agreement),
        which Warrant Agreement is hereby incorporated by reference in and made a
        part
        of this instrument and is hereby referred to for a description of the rights,
        limitation of rights, obligations, duties and immunities thereunder of the
        Warrant Agent, the Company and the Holders (“Holders” meaning, from time to
        time, the registered holders of the warrant issued thereunder). To the extent
        any provisions of this Series E Warrant Certificate conflicts with any
        provision of the Warrant Agreement, the provisions of the Warrant Agreement
        shall apply. A copy of the Warrant Agreement may be obtained by the Holder
        hereof upon written request to the Company at 2635 North Crescent Ridge
        Drive, The Woodlands, Texas 77381 Attention: Investor Relations. Capitalized
        terms not defined herein have the meanings ascribed thereto in the Warrant
        Agreement.

       

      This
        Series E Warrant may be exercised, in whole or in part, at any time on or
        after _______ __, 2008 and on or before the Expiration Date, subject to the
        terms of the Warrant Agreement, by surrendering this Warrant Certificate,
        with
        the Form of Election to Purchase set forth hereon properly completed and
        executed, together with payment of the Aggregate Exercise Price in accordance
        with Section 9 of the Warrant Agreement in the case of a Cash Exercise.
        Each exercise must be for a whole number of Warrant Shares. In the event
        that
        upon any exercise of the Series E Warrant evidenced hereby the number of
        shares of Common Stock acquired shall be less than the total number of shares
        of
        Common Stock which may be purchased pursuant to this Series E Warrant,
        there shall be issued to the Holder hereof or such Holder’s assignee a new
        Series E Warrant Certificate evidencing the unexercised portion of this
        Series E Warrant.

       

      
        
          
          

        

        
          Exhibit
            A - Page 1

          
            

          

        

        
          
          

        

      

       

      The
        Warrant Agreement provides that upon the occurrence of certain events the
        Exercise Price set forth on this Series E Warrant Certificate may, subject
        to certain conditions, be adjusted, and that upon the occurrence of certain
        events the number of shares of Common Stock and/or the type of securities
        or
        other property issuable upon the exercise of this Series E Warrant shall be
        adjusted. No fractions of a share of Common Stock will be issued upon the
        exercise of this Series E Warrant, but the Company will pay the cash value
        thereof determined as provided in the Warrant Agreement.

       

      The
        Warrant Agreement provides in certain circumstances for a call right on the
        part
        of the Company, pursuant to which this Series E Warrant may be
        terminated.

       

      Series E
        Warrant Certificates, when surrendered at the office of the Warrant Agent
        by the
        registered Holder thereof in person or by such Holder’s legal representative or
        attorney duly appointed and authorized in writing, may be exchanged, in the
        manner and subject to the limitations provided in the Warrant Agreement,
        but
        without payment of any service charge, for another Series E Warrant
        Certificate or Series E Warrant Certificates of like tenor evidencing in
        the aggregate the right to purchase a like number of Warrant
        Shares.

       

      Each
        taker
        and holder of this Series E Warrant Certificate, by taking or holding the
        same, consents and agrees that the holder of this Series E Warrant
        Certificate when duly endorsed in blank may be treated by the Company, the
        Warrant Agent and all other persons dealing with this Series E Warrant
        Certificate as the absolute owner hereof for any purpose and as the person
        entitled to exercise the rights represented hereby or the person entitled
        to the
        transfer hereof on the register of the Company maintained by the Warrant
        Agent,
        any notice to the contrary notwithstanding, provided that until such transfer
        on
        such register, the Company and the Warrant Agent may treat the registered
        Holder
        hereof as the owner for all purposes.

       

      This
        Series E Warrant does not entitle any Holder to any of the rights of a
        shareholder of the Company.

       

      This
        Series E Warrant Certificate and the Warrant Agreement are subject to
        amendment as provided in the Warrant Agreement.

       

      This
        Series E Warrant Certificate shall not be valid or obligatory for any
        purpose until it shall have been countersigned by the Warrant
        Agent.

       

      [The
        remainder of this page has been left intentionally blank.]

       

      
        
          
          

        

        
          Exhibit
            A - Page 2

          
            

          

        

        
          
          

        

      

       

      IN
        WITNESS WHEREOF, the undersigned have caused this Series E Warrant
        Certificate to be executed as of the date set forth below.

       

      
        	 	OPEXA
                THERAPEUTICS, INC.	 
	 	 	 	 
	
                 

              	
                By:
                  

              	 	 
	 	 Name	 David
                B. McWilliams	 
	 	 Title 	President	 
	 	 	 	 


      

       

       

      
        	
                 

              	
                By:
                  

              	/s/ 	 
	 	 Name	 	 
	 	 Title	 	 
	 	 	 	 
	 	 DATED:
                ______________________________, 2008 	 


      

       

      
         

        
          	 	 Countersigned:	 
	 	 	 
	 	
                  CONTINENTAL
                    STOCK TRANSFER & TRUST COMPANY,

                  as
                    Warrant Agent

                	 
	 	 	 	 
	
                   

                	
                  By:
                    

                	 	 
	 	 Name	 	 
	 	 Title 	 	 
	 	 	 	 


        

         

        
          
            
            

          

          
            Exhibit
              A - Page 3

            
              

            

          

          
            
            

          

        

      

      


      FORM
        OF
        ELECTION TO PURCHASE

       

      


      To
        Opexa
        Therapeutics, Inc.:

      


      In
        accordance with the Series E Warrant Certificate enclosed with this Form of
        Election to Purchase, the undersigned hereby irrevocably elects to exercise
        the
        Series E Warrant with respect to Warrant Shares in accordance with the
        terms of the Warrant Agreement.

       

      1.           Form
        of Exercise Price.  The Holder intends that payment of the
        Exercise Price shall be made as:

       

      a
        Cash Exercise;

       

      a
        Cashless Exercise; or

       

      The
        Holder
        understands that any Cashless Exercise is subject to compliance with all
        the
        terms of the Warrant Agreement.

      


      2.           Payment
        of Exercise Price.  If the Holder has elected a Cash Exercise with
        respect to some or all of the Warrant Shares to be issued pursuant hereto,
        the
        Holder shall send via wire transfer to the account of the Company the sum
        of $
        ______________ in immediately available funds, which sum represents the
        Aggregate Exercise Price (as defined in the Warrant Agreement) for the number
        of
        shares of Common Stock to which this Form of Election to Purchase relates,
        together with any applicable taxes payable by the undersigned pursuant to
        the
        Series E Warrant.

       

      The
        undersigned requests that certificates for the shares of Common Stock issuable
        upon this exercise be issued in the name of

       

      
        
          	 	
                  Name:

                	 	 
	 	 	 	 
	 	
                  Address:

                	 	 
	 	 	 	 
	 	 	 	 
	 	 	 	 
	 	 	 	 
	 	 	 	 
	 	
                  Social
                    Security or Tax I.D. No.:
                    _________________________

                


        

      

       

      
        
          
          

        

        
          
            Form
              of Election to Purchase

          

          
            

          

        

        
          
          

        

      

       

      WARRANT
        SHARES EXERCISE LOG

       

      
        
          	
                  
                    Date

                  

                	 	
                  
                    Number
                      of Warrant Shares Available to be Exercised

                  

                	 	
                  
                    Number
                      of Warrant Shares Exercised

                  

                	 	
                  
                    Number
                      of Warrant Shares Remaining to be
                      Exercised

                  

                
	 	 	 	 	 	 	 
	 	 	 	 	 	 	 


        

      

       

      
        
          
          

        

        
          
            Warrant
              Shares Exercise Log

          

          
            

          

        

        
          
          

        

      

       

      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 Series E Warrant Certificate to purchase
        ________________ shares of Common Stock of Opexa Therapeutics, Inc. to which
        the
        within Series E Warrant Certificate relates and appoints
        ________________________________ attorney to transfer said right on the books
        of
        Opexa Therapeutics, Inc. with full power of substitution in the
        premises.

       

      Dated:  __________________,
        20_____

       

      
        
          	 	 
	 	
                  (Signature
                    must conform in all respects to name of holder as specified on
                    the front
                    page of the Series E Warrant Certificate)

                
	
                   

                	 
	 	
                  Address
                    of Transferee:

                
	 	 
	 	 
	 	 
	 	 
	 	
                   

                  In
                    the presence of:

                
	 	 


        

      

       

       

      
        Form
          of Assignment