COMMON STOCK PURCHASE WARRANT To Purchase 1,150,000 Shares of Common Stock of CALLISTO PHARMACEUTICALS, INC.

Exhibit 3.1

NEITHER THIS SECURITY NOR THE SECURITIES INTO WHICH THIS SECURITY IS EXERCISABLE HAVE BEEN REGISTERED WITH THE SECURITIES AND EXCHANGE COMMISSION OR THE SECURITIES COMMISSION OF ANY STATE IN RELIANCE UPON AN EXEMPTION FROM REGISTRATION UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE “SECURITIES ACT”), AND, ACCORDINGLY, MAY NOT BE OFFERED OR SOLD EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR PURSUANT TO AN AVAILABLE EXEMPTION FROM, OR IN A TRANSACTION NOT SUBJECT TO, THE REGISTRATION REQUIREMENTS OF THE SECURITIES ACT AND IN ACCORDANCE WITH APPLICABLE STATE SECURITIES LAWS AS EVIDENCED BY A LEGAL OPINION OF COUNSEL TO THE TRANSFEROR TO SUCH EFFECT, THE SUBSTANCE OF WHICH SHALL BE REASONABLY ACCEPTABLE TO THE COMPANY.

September 25, 2007

WF-1

COMMON STOCK PURCHASE WARRANT

To Purchase 1,150,000 Shares of Common Stock of

CALLISTO PHARMACEUTICALS, INC.

THIS COMMON STOCK PURCHASE WARRANT (the “Warrant”) certifies that, for value received, Capebio LLC (the “Holder”), is entitled, upon the terms and subject to the limitations on exercise and the conditions hereinafter set forth and subject to this Warrant being vested as set forth at the end of this paragraph, at any time on or after the date hereof (the “Initial Exercise Date”) and on or prior to the close of business on the seventh anniversary of the Initial Exercise Date (the “Expiration Date”) but not thereafter, to subscribe for and purchase from Callisto Pharmaceuticals, Inc., a Delaware corporation (the “Company”), up to 1,150,000 shares (the “Warrant Shares”) of Common Stock, par value $.0001 per share, of the Company (the “Common Stock”). The purchase price of one share of Common Stock under this Warrant shall be equal to the Exercise Price, as defined in Section 1(b). Subject to the other provisions of this Warrant, provided the Holder or Xxxxxx’s assignee is engaged as a consultant, officer, director or employee of the Company or any of the Company’s subsidiaries, this Warrant shall vest and become exercisable in installments of 225,000 Warrant Shares on each of the first four anniversaries of the Initial Exercise Date. The remaining 250,000 will vest (a “Subsidiary Exit Event Vesting Event”), immediately prior to the consummation of a Subsidiary Exit Event (as defined below); provided, that such Subsidiary Exit Event occurs on or prior to October 1, 2009 and the Enterprise Value of the Sub (as defined below) determined in connection with the Subsidiary Exit Event is no less than $250,000,000. For purposes hereof, “Subsidiary Exit Event” shall mean (A) any consolidation or merger of Synergy Advanced Pharmaceuticals, Inc. (the “Sub”) in which the Sub is not the continuing or surviving corporation or pursuant to which shares of the Sub’s capital stock would be converted into cash, securities or other property, other than a merger of the Sub in which the holders of the Sub’s voting capital stock immediately

prior to the merger have substantially the same proportionate ownership of common stock of the surviving corporation immediately after the merger, or (B) any sale, lease, exchange or other transfer (in one transaction or a series of related transactions) of all or substantially all the assets of the Sub; (ii) the stockholders of the Sub shall approve any plan or proposal for the liquidation or dissolution of the Sub, or (iii) any person (as such term is used in Sections 13(d) and 14(d)(2) of the Securities Exchange Act of 1934 (the “Exchange Act”)) shall become the beneficial owner (within the meaning of Rule 13d-3 under the Exchange Act) of securities of the Sub representing 50% or more of the combined voting power of the Sub’s then outstanding capital stock ordinarily (and apart from rights accruing in special circumstances or upon the conversion of convertible securities or the exercise of warrants issued in connection with financing) having the right to vote in the election of directors, as a result of a tender or exchange offer, open market purchases, privately negotiated purchases or otherwise. For purposes hereof, “Enterprise Value” shall mean shall mean the total proceeds and other consideration paid or received or to be paid or received in connection with the Subsidiary Exit Event (which consideration shall be deemed to include amounts in escrow), including, without limitation: (i) cash (including retained cash); (ii) notes, securities and other property (including any retained property in addition to cash); (iii) liabilities, including all debt, pension liabilities and guarantees, assumed, refinanced, or extinguished which do not result in a purchase price adjustment under the definitive transaction agreements); (iv) payments made in installments; (v) consideration which is contingent upon the occurrence of some future event (e.g., the realization of earnings projections); and (vi) payments in respect of non-compete covenants or above market rate payments in respect of consulting or similar services to be rendered directly or indirectly to the acquiror following the closing of a Subsidiary Exit Event. [

Section 1. Exercise.

a) Exercise of Warrant. Exercise of the purchase rights represented by this Warrant may be made at any time or times on or after the Initial Exercise Date and on or before the Expiration Date by delivery to the Company of a duly executed facsimile copy of the Notice of Exercise Form annexed hereto (or such other office or agency of the Company as it may designate by notice in writing to the registered Holder at the address of such Holder appearing on the books of the Company). Exercise of the Warrant shall be deemed to have occurred when Xxxxxx shall have surrendered this Warrant to the Company and the Company shall have received payment of the aggregate Exercise Price of the shares thereby purchased by wire transfer or cashier’s check drawn on a United States bank. For purposes hereof, “Trading Day” shall mean a day on which the Common Stock is traded on a Trading Market (as defined below).

b) Exercise Price. The exercise price of the Common Stock under this Warrant shall be $0.47, subject to adjustment hereunder (the “Exercise Price”).

c) Net Exercise. Notwithstanding anything to the contrary contained in this Section 1, at any time after the one year anniversary of the Original Issue Date this

Warrant may also be exercised at such time by means of a “cashless exercise” in which the Holder shall be entitled to receive a certificate for the number of Warrant Shares equal to the quotient obtained by dividing [(A-B) x (C)] by (A), where:

(A) = the volume weighted average trading price of the Common Stock on the principal Trading Market (as defined below) over the twenty (20) consecutive Trading Days immediately preceding the date of such election (“VWAP”);

(B) = the Exercise Price of this Warrant, as adjusted; and

(C) = the total number of Warrant Shares issuable upon exercise of this Warrant (or a lesser number of Warrant Shares if so requested by the Holder) in accordance with the terms of this Warrant by means of a cash exercise rather than a cashless exercise.

For purposes hereof, “Trading Market” shall mean the following markets or exchanges on which the Common Stock is listed or quoted for trading on the date in question: the Over-The-Counter Bulletin Board, the Nasdaq Global Market, the American Stock Exchange, the New York Stock Exchange or the Nasdaq Capital Market .

d) Mechanics of Exercise.

i. Authorization of Warrant Shares. The Company covenants that all Warrant Shares which may be issued upon the exercise of the purchase rights represented by this Warrant will, upon exercise of the purchase rights represented by this Warrant, be duly authorized, validly issued, fully paid and nonassessable and free from all taxes, liens and charges in respect of the issue thereof (other than taxes in respect of any transfer occurring contemporaneously with such issue). The Company covenants that during the period the Warrant is outstanding, it will reserve from its authorized and unissued Common Stock a sufficient number of shares to provide for the issuance of the Warrant Shares upon the exercise of any purchase rights under this Warrant. The Company further covenants 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 the Warrant Shares upon the exercise of the purchase rights under this Warrant. The Company will take all such reasonable action as may be necessary to assure that such Warrant Shares may be issued as provided herein without violation of any applicable law or regulation, or of any requirements of the Trading Market upon which the Common Stock may be listed.

ii. Delivery of Certificates Upon Exercise. Certificates for shares purchased hereunder shall be transmitted by the transfer agent of the Company to the Holder by crediting the account of the Holder’s prime broker with the Depository Trust Company through its Deposit

Withdrawal Agent Commission (“DWAC”) system if the Company is a participant in such system, and otherwise by physical delivery to the address specified by the Holder in the Notice of Exercise within 3 Trading Days from the delivery to the Company of the Notice of Exercise Form, surrender of this Warrant and payment of the aggregate Exercise Price as set forth above (“Warrant Share Delivery Date”). This Warrant shall be deemed to have been exercised on the date the Exercise Price is received by the Company. The Warrant Shares shall be deemed to have been issued, and Holder or any other person so designated to be named therein shall be deemed to have become a holder of record of such shares for all purposes, as of the date the Warrant has been exercised by payment to the Company of the Exercise Price and all taxes required to be paid by the Holder, if any, prior to the issuance of such shares, have been paid.

iii. Delivery of New Warrants Upon Exercise. If this Warrant shall have been exercised in part, the Company shall, at the time of delivery of the certificate or certificates representing Warrant Shares, deliver to Holder a new Warrant evidencing the rights of Holder to purchase the unpurchased Warrant Shares called for by this Warrant, which new Warrant shall in all other respects be identical with this Warrant.

iv. No Fractional Shares or Scrip. No fractional shares or scrip representing fractional shares shall be issued upon the exercise of this Warrant. As to any fraction of a share which Holder would otherwise be entitled to purchase upon such exercise, the Company shall pay a cash adjustment in respect of such final fraction in an amount equal to such fraction multiplied by the Exercise Price.

v. Charges, Taxes and Expenses. Issuance of certificates for Warrant Shares shall be made without charge to the Holder for any issue or transfer tax or other incidental expense in respect of the issuance of such certificate, all of which taxes and expenses shall be paid by the Company, and such certificates shall be issued in the name of the Holder or in such name or names as may be directed by the Holder; provided, however, that in the event certificates for Warrant Shares are to be issued in a name other than the name of the Holder, this Warrant when surrendered for exercise shall be accompanied by the Assignment Form attached hereto duly executed by the Holder; and the Company may require, as a condition thereto, the payment of a sum sufficient to reimburse it for any transfer tax incidental thereto.

vi. Closing of Books. The Company will not close its stockholder books or records in any manner which prevents the timely exercise of this Warrant, pursuant to the terms hereof.

e) Termination of Warrant. Subject to the first paragraph of this Warrant and Section 2(e), if the Holder’s services to the Company or any subsidiary corporation of the Company is terminated voluntarily by the Holder or for Cause (as defined below) by the Company, this Warrant shall expire forthwith, but if such termination is for any other reason (except death or disability), then this Warrant may not be exercised at any time later than three (3) months after such termination and then only to purchase those number Warrant Shares subject to this Warrant that the Holder was entitled to purchase upon exercise of this Warrant, prior to such termination of the Holder’s employment or service. If the Holder dies (i) while employed by or providing services to the Company or a subsidiary corporation of the Company, or (ii) within three (3) months after termination of the Holder’s employment or services, then this Warrant may be exercised by the estate of the Holder, or by a person who acquired the right to exercise this Warrant by bequest or inheritance or by reason of the death of the Holder, at any time within one (1) year after such death. If the Holder’s employment or services with the Company or such subsidiary are terminated because of permanent and total disability while employed by or in the service of the Company or such subsidiary, this Warrant may be exercised at any time within one (1) year after termination of the Holder’s employment or service due to the disability; provided, however, that nothing in this Section 3 shall extend the right to purchase Warranted Shares which could not be purchased by the Holder prior to the termination of his employment with the Company or such subsidiary. For purposes of this Agreement “Cause” shall mean (i) any act or omission that constitutes a material breach by the Holder of any agreement between the Holder and the Company or any subsidiary thereof under which the Holder provides services (each a “Service Agreement”); (ii) the commission by the Holder or any of Holder’s affiliates of a dishonest, illegal or wrongful act involving fraud, misrepresentation or moral turpitude which causes damage to Company’s business, has a material negative impact on the market price of he Company’s Common Stock; or reputation; or (iii) willful failure or refusal to perform services set forth under the parties’ Services Agreement. In the event that the definition of Cause herein, is inconsistent with a definition of cause contained in a agreement between the Company or a subsidiary of the Company, on the one side, and the Holder or an affiliate of the Holder, on the other side, the provisions of such subsequent agreement shall be controlling.

Section 2. Certain Adjustments.

a) Stock Dividends and Splits. If the Company, at any time while this Warrant is outstanding: (i) pays a stock dividend or otherwise makes a distribution or distributions on shares of its Common Stock or any other equity or equity equivalent securities payable in shares of Common Stock (which, for avoidance of doubt, shall not include any shares of Common Stock issued by the Company upon exercise of this Warrant), (ii) subdivides outstanding shares of Common Stock into a larger number of shares, (iii) combines (including by way of reverse stock split) outstanding shares of Common Stock into a smaller number of shares, or (iv) issues by reclassification of shares of the Common Stock any shares of capital stock of the Company, then in each case the Exercise Price shall be multiplied by a fraction of which the numerator shall be the number of shares of Common Stock (excluding treasury shares, if any) outstanding

before such event and of which the denominator shall be the number of shares of Common Stock outstanding after such event and the number of shares issuable upon exercise of this Warrant shall be proportionately adjusted. Any adjustment made pursuant to this Section 2(a) shall become effective immediately after the record date for the determination of stockholders entitled to receive such dividend or distribution and shall become effective immediately after the effective date in the case of a subdivision, combination or re-classification.

b) Pro Rata Distributions. If the Company, at any time prior to the Expiration Date, shall distribute to all holders of Common Stock (and not to Holders of the Warrants) evidences of its indebtedness or assets or rights or warrants to subscribe for or purchase any security other than the Common Stock, then in each such case the Exercise Price shall be adjusted by multiplying the Exercise Price in effect immediately prior to the record date fixed for determination of stockholders entitled to receive such distribution by a fraction of which the denominator shall be the VWAP determined as of the record date mentioned above, and of which the numerator shall be such VWAP on such record date less the then per share fair market value at such record date of the portion of such assets or evidence of indebtedness so distributed applicable to one outstanding share of the Common Stock as determined by the Board of Directors in good faith. In either case the adjustments shall be described in a statement provided to the Holders of the portion of assets or evidences of indebtedness so distributed or such subscription rights applicable to one share of Common Stock. Such adjustment shall be made whenever any such distribution is made and shall become effective immediately after the record date mentioned above.

c) Calculations. All calculations under this Section 2 shall be made to the nearest cent or the nearest 1/100th of a share, as the case may be. The number of shares of Common Stock outstanding at any given time shall not include shares of Common Stock owned or held by or for the account of the Company, and the description of any such shares of Common Stock shall be considered on issue or sale of Common Stock. For purposes of this Section 2 the number of shares of Common Stock deemed to be issued and outstanding as of a given date shall be the sum of the number of shares of Common Stock (excluding treasury shares, if any) issued and outstanding.

d) Notice to Holders.

i. Adjustment to Exercise Price. Whenever the Exercise Price is adjusted pursuant to this Section 2, the Company shall promptly mail to each Holder a notice setting forth the Exercise Price after such adjustment and setting forth a brief statement of the facts requiring such adjustment.

ii. Notice to Allow Exercise by Xxxxxx. If (A) the Company shall declare a dividend (or any other distribution) on the Common Stock; (B) the Company shall declare a special nonrecurring cash dividend on or a redemption of the Common Stock; (C) the Company shall authorize the granting to all holders of the Common Stock rights or warrants to subscribe for or purchase any shares of capital stock of any class or of any

rights; (D) the approval of any stockholders of the Company shall be required in connection with any reclassification of the Common Stock, any consolidation or merger to which the Company is a party, any sale or transfer of all or substantially all of the assets of the Company, of any compulsory share exchange whereby the Common Stock is converted into other securities, cash or property; (E) the Company shall authorize the voluntary or involuntary dissolution, liquidation or winding up of the affairs of the Company; then, in each case, the Company shall cause to be mailed to the Holder at its last addresses as it shall appear upon the Warrant Register of the Company, at least 15 calendar days prior to the applicable record or effective date hereinafter specified, a notice stating (x) the date on which a record is to be taken for the purpose of such dividend, distribution, redemption, rights or warrants, or if a record is not to be taken, the date as of which the holders of the Common Stock of record to be entitled to such dividend, distributions, redemption, rights or warrants are to be determined or (y) the date on which such reclassification, consolidation, merger, sale, transfer or share exchange is expected to become effective or close, and the date as of which it is expected that holders of the Common Stock of record shall be entitled to exchange their shares of the Common Stock for securities, cash or other property deliverable upon such reclassification, consolidation, merger, sale, transfer or share exchange; provided, that the failure to mail such notice or any defect therein or in the mailing thereof shall not affect the validity of the corporate action required to be specified in such notice. The Holder is entitled to exercise this Warrant during the 15-day period commencing the date of such notice to the effective date of the event triggering such notice.

e) Change of Control In the event there shall have been a Change in Control of the Company (as defined below), all unvested Warrants shall immediately and irrevocably vest immediately prior to the consummation of such Change in Control of the Company, and be exercisable until the Expiration Date, notwithstanding any of the provisions of Section 1e, above. For purposes of this Agreement, a “Change in Control of the Company” shall be deemed to have occurred if (i) there shall be consummated (A) any consolidation or merger of the Company in which the Company is not the continuing or surviving corporation or pursuant to which shares of the Company’s Common Stock would be converted into cash, securities or other property, other than a merger of the Company in which the holders of the Company’s Common Stock immediately prior to the merger have substantially the same proportionate ownership of common stock of the surviving corporation immediately after the merger, or (B) any sale, lease, exchange or other transfer (in one transaction or a series of related transactions) of all or substantially all the assets of the Company; (ii) the stockholders of the Company shall approve any plan or proposal for the liquidation or dissolution of the Company, (iii) any person (as such term is used in Sections 13(d) and 14(d)(2) of the Exchange Act, other than the Company or any employee benefit plan sponsored by the Company, shall become the beneficial owner (within the meaning of Rule 13d-3 under the Exchange Act) of securities of the Company representing 50% or more of the combined voting power of the

Company’s then outstanding securities ordinarily (and apart from rights accruing in special circumstances or upon the conversion of convertible securities or the exercise of warrants issued in connection with financing) having the right to vote in the election of directors, as a result of a tender or exchange offer, open market purchases, privately negotiated purchases or otherwise, or (iv) at any time during a period of two consecutive years, individuals who at the beginning of such period constituted the Board of Directors of the Company shall cease for any reason to constitute at least a majority thereof, unless the election or the nomination for election by the Company’s stockholders of each new director during such two-year period was approved by a vote of at least two-thirds of the directors then still in office who were directors at the beginning of such two-year period.

f) Voluntary Adjustment By Company. The Company may at any time during the term of this Warrant reduce the then current Exercise Price to any amount and for any period of time deemed appropriate by the Board of Directors of the Company.

Section 3. Transfer of Warrant.

a) Transferability. This Warrant may not be transferred except in connection with a “Permitted Transfer” defined below. In connection with a Permitted Transfer, subject to compliance with any applicable securities laws and the conditions set forth in Sections 4(a) and 3(d) hereof, this Warrant and all rights hereunder are transferable, in whole or in part, upon surrender of this Warrant at the principal office of the Company, together with a written assignment of this Warrant substantially in the form attached hereto duly executed by the Holder or its agent or attorney and funds sufficient to pay any transfer taxes payable upon the making of such transfer. Upon such surrender and, if required, such payment, the Company shall execute and deliver a new Warrant or Warrants in the name of the assignee or assignees and in the denomination or denominations specified in such instrument of assignment, and shall issue to the assignor a new Warrant evidencing the portion of this Warrant not so assigned, and this Warrant shall promptly be cancelled. A Warrant, if properly assigned, may be exercised by a new holder for the purchase of Warrant Shares without having a new Warrant issued. For the purposes of this Warrant, “transfer” means to sell or in any way directly or indirectly transfer, assign, distribute, pledge, encumber or otherwise dispose of, either voluntarily or involuntarily. Any transfer in violation of the prohibition contained herein shall be void and the Expiration Date of any Warrants purported to be transferred in violation of this provision shall be deemed to be the date immediately preceding such purported transfer.

b) New Warrants. This Warrant may be divided or combined with other Warrants upon presentation hereof at the aforesaid office of the Company, together with a written notice specifying the names and denominations in which new Warrants are to be issued, signed by the Holder or its agent or attorney. Subject to compliance with Section 3(a), as to any transfer which may be involved in such division or combination, the Company shall execute and deliver a new Warrant or Warrants in exchange for the Warrant or Warrants to be divided or combined in accordance with such notice.

c) Warrant Register. The Company shall register this Warrant, upon records to be maintained by the Company for that purpose (the “Warrant Register”), in the name

of the record Holder hereof from time to time. The Company may deem and treat the registered Holder of this Warrant as the absolute owner hereof for the purpose of any exercise hereof or any distribution to the Holder, and for all other purposes, absent actual notice to the contrary.

d) Transfer Restrictions. If, at the time of the surrender of this Warrant in connection with any transfer of this Warrant, the transfer of this Warrant shall not be registered pursuant to an effective registration statement under the Securities Act and under applicable state securities or blue sky laws, the Company may require, as a condition of allowing such transfer (i) that the Holder or transferee of this Warrant, as the case may be, furnish to the Company a written opinion of counsel (which opinion shall be in form, substance and scope customary for opinions of counsel in comparable transactions) to the effect that such transfer may be made without registration under the Securities Act and under applicable state securities or blue sky laws, (ii) that the holder or transferee execute and deliver to the Company an investment letter in form and substance acceptable to the Company and (iii) that the transferee be an “accredited investor” as defined in Rule 501(a)promulgated under the Securities Act or a qualified institutional buyer as defined in Rule 144A(a) under the Securities Act.

e) “Permitted Transfer” means, with respect to any person, (i) a transfer to a trust for the benefit of such person’s spouse or issue or to a family partnership, limited liability company or similar entity of which the members are solely such person, or such person’s spouse or issue and as to which such person exercises voting control, (ii) a transfer to an affiliate of such person, or (iii) if such person is a limited or general partnership or limited liability company, a transfer to its partners or members, as the case may be, in connection with a distribution of securities held by such person to its partners.

Section 4. Miscellaneous.

a) No Rights as Stockholder Until Exercise. This Warrant does not entitle the Holder to any voting rights or other rights as a stockholder of the Company prior to the exercise hereof. Upon the surrender of this Warrant and the payment of the aggregate Exercise Price (or by means of a cashless exercise), the Warrant Shares so purchased shall be and be deemed to be issued to such Holder as the record owner of such shares as of the close of business on the later of the date of such surrender or payment.

b) Loss, Theft, Destruction or Mutilation of Warrant. The Company covenants that upon receipt by the Company of evidence reasonably satisfactory to it of the loss, theft, destruction or mutilation of this Warrant or any stock certificate relating to the Warrant Shares, and in case of loss, theft or destruction, of indemnity or security reasonably satisfactory to it (which, in the case of the Warrant, shall not include the posting of any bond), and upon surrender and cancellation of such Warrant or stock certificate, if mutilated, the Company will make and deliver a new Warrant or stock certificate of like tenor and dated as of such cancellation, in lieu of such Warrant or stock certificate.

c) Saturdays, Sundays, Holidays, etc. If the last or appointed day for the taking of any action or the expiration of any right required or granted herein shall be a Saturday, Sunday or a legal holiday, then such action may be taken or such right may be exercised on the next succeeding day not a Saturday, Sunday or legal holiday.

d) Authorized Shares. The Company covenants that during the period the Warrant is outstanding, it will reserve from its authorized and unissued Common Stock a sufficient number of shares to provide for the issuance of the Warrant Shares upon the exercise of any purchase rights under this Warrant. The Company further covenants 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 the Warrant Shares upon the exercise of the purchase rights under this Warrant. The Company will take all such reasonable action as may be necessary to assure that such Warrant Shares may be issued as provided herein without violation of any applicable law or regulation, or of any requirements of the Trading Market upon which the Common Stock may be listed. Except and to the extent as waived or consented to by the Holder, the Company shall not by any action, including, without limitation, amending its certificate of incorporation or through any reorganization, transfer of assets, consolidation, merger, dissolution, issue or sale of securities or any other voluntary action, avoid or seek to avoid the observance or performance of any of the terms of this Warrant, but will at all times in good faith assist in the carrying out of all such terms and in the taking of all such actions as may be necessary or appropriate to protect the rights of Holder as set forth in this Warrant against impairment. Without limiting the generality of the foregoing, the Company will (a) not increase the par value of any Warrant Shares above the amount payable therefor upon such exercise immediately prior to such increase in par value, (b) take all such action as may be necessary or appropriate in order that the Company may validly and legally issue fully paid and nonassessable Warrant Shares upon the exercise of this Warrant, and (c) use commercially reasonable efforts to obtain all such authorizations, exemptions or consents from any public regulatory body having jurisdiction thereof as may be necessary to enable the Company to perform its obligations under this Warrant. Before taking any action which would result in an adjustment in the number of Warrant Shares for which this Warrant is exercisable or in the Exercise Price, the Company shall obtain all such authorizations or exemptions thereof, or consents thereto, as may be necessary from any public regulatory body or bodies having jurisdiction thereof.

e) Restrictions. The Holder acknowledges that the Warrant Shares acquired upon the exercise of this Warrant, if not registered, will have restrictions upon resale imposed by state and federal securities laws.

f) Nonwaiver and Expenses. No course of dealing or any delay or failure to exercise any right hereunder on the part of Holder shall operate as a waiver of such right or otherwise prejudice Xxxxxx’s rights, powers or remedies, notwithstanding the fact that all rights hereunder terminate on the Expiration Date. If the Company willfully and knowingly fails to comply with any provision of this Warrant, which results in any

damages to the Holder, the Company shall pay to Holder such amounts as shall be sufficient to cover any costs and expenses including, but not limited to, reasonable attorneys’ fees, including those of appellate proceedings, incurred by Holder in collecting any amounts due pursuant hereto or in otherwise enforcing any of its rights, powers or remedies hereunder.

g) Notices. Any notice, request or other document required or permitted to be given or delivered to the Holder by the Company shall be in writing and shall be deemed effective when received and shall be deliverable in person, or by facsimile transmission (with confirmation of receipt), or by mail, postage prepaid, for delivery as registered or certified mail addressed to the Holder at 0000 Xxxxx Xxxxxx, Xxxxx Xxxxx, Xxxxxxxx 00000.

h) Limitation of Liability. No provision hereof, in the absence of any affirmative action by Holder to exercise this Warrant or purchase Warrant Shares, and no enumeration herein of the rights or privileges of Holder, shall give rise to any liability of Holder for the purchase price of any Common Stock or as a stockholder of the Company, whether such liability is asserted by the Company or by creditors of the Company.

i) Remedies. Holder, in addition to being entitled to exercise all rights granted by law, including recovery of damages, will be entitled to specific performance of its rights under this Warrant. The Company agrees that monetary damages would not be adequate compensation for any loss incurred by reason of a breach by it of the provisions of this Warrant and hereby agrees to waive the defense in any action for specific performance that a remedy at law would be adequate.

j) Successors and Assigns. Subject to applicable securities laws, this Warrant and the rights and obligations evidenced hereby shall inure to the benefit of and be binding upon the successors of the Company and the successors and permitted assigns of Holder. The provisions of this Warrant are intended to be for the benefit of all Holders from time to time of this Warrant and shall be enforceable by any such Holder or holder of Warrant Shares.

k) Amendment. This Warrant may be modified or amended or the provisions hereof waived with the written consent of the Company and the Holder.

l) Severability. Wherever possible, each provision of this Warrant shall be interpreted in such manner as to be effective and valid under applicable law, but if any provision of this Warrant shall be prohibited by or invalid under applicable law, such provision shall be ineffective to the extent of such prohibition or invalidity, without invalidating the remainder of such provisions or the remaining provisions of this Warrant.

m) Headings. The headings used in this Warrant are for the convenience of reference only and shall not, for any purpose, be deemed a part of this Warrant.

********************

IN WITNESS WHEREOF, the Company has caused this Warrant to be executed by its officer thereunto duly authorized.

Dated: September 25, 2007

	CALLISTO PHARMACEUTICALS, INC.


	By:
		Name:
		Title:

NOTICE OF EXERCISE

TO: CALLISTO PHARMACEUTICALS, INC.

(1) The undersigned hereby elects to purchase Warrant Shares of the Company pursuant to the terms of the attached Warrant, and tenders herewith payment of the exercise price in full, together with all applicable transfer taxes, if any.

(2) Payment shall take the form of (check applicable box):

o in lawful money of the United States; or

o the cancellation of such number of Warrant Shares as is necessary, in accordance with the formula set forth in subsection 1(c), to exercise this Warrant with respect to the maximum number of Warrant Shares purchasable pursuant to the cashless exercise procedure set forth in subsection 1(c).

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

The Warrant Shares shall be delivered to the following:

(4) Accredited Investor. The undersigned is an “accredited investor” as defined in Regulation D promulgated under the Securities Act of 1933, as amended.

[SIGNATURE OF HOLDER]

Name of Investing Entity:
Signature of Authorized Signatory of Investing Entity:
Name of Authorized Signatory:
Title of Authorized Signatory:
Date:

ASSIGNMENT FORM

(To assign the foregoing warrant, execute
this form and supply required information.
Do not use this form to exercise the warrant.)

FOR VALUE RECEIVED, the foregoing Warrant and all rights evidenced thereby are hereby assigned to

whose address is

Dated: ,

	Holder’s Signature:
	Holder’s Address:

NOTE: The signature to this Assignment Form must correspond with the name as it appears on the face of the Warrant, without alteration or enlargement or any change whatsoever, and must be guaranteed by a bank or trust company. Officers of corporations and those acting in a fiduciary or other representative capacity should file proper evidence of authority to assign the foregoing Warrant.

Document Metadata

Table of Contents

COMMON STOCK PURCHASE WARRANT To Purchase 1,150,000 Shares of Common Stock of CALLISTO PHARMACEUTICALS, INC.

Document Metadata