Exhibit 2.1

EXECUTION COPY

ASTEX THERAPEUTICS LIMITED

and

SUPERGEN INC

IMPLEMENTATION AGREEMENT

INDEX

PARTIES

(1)                                  ASTEX THERAPEUTICS LIMITED whose registered office is at 436 Cambridge Science Park, Milton Road, Cambridge, CB4 0QA, United Kingdom (the “Company”); and

(2)                                  SUPERGEN INC whose registered office is at 4140 Dublin Blvd, Suite 200, Dublin, CA 94568, United States of America (the “Purchaser or SuperGen”).

INTRODUCTION

A                                      The Purchaser intends to acquire the entire share capital of the Company, to be implemented by way of, and the Company has agreed to implement, the Scheme on the terms and subject to the conditions to be set out in the Scheme Document.

B                                        Each of the Company Board and the Purchaser Board has approved this Agreement and the Transactions.

C                                        The parties are entering into this Agreement to set out certain commitments to implement the Scheme and otherwise in connection with the Acquisition and certain matters relating to the conduct of the business of the Company and its Group.

D                                       The Company has obtained the Company Irrevocable Voting Undertakings and the Purchaser has obtained the Purchaser Support Agreements.

E                                         Pursuant to the Scheme Terms and Conditions that form part of the Scheme Document contained in Schedule 2, the Sellers’ Representative shall enter into the Lock-Up Agreements on behalf of the Restricted Shareholders under power of attorney conferred by operation of the Scheme.

IT IS AGREED THAT:

1.                                      DEFINITIONS

In this Agreement (but not in the Press Announcement or the Scheme Document) unless the context otherwise requires:

“Act” means the Companies Act 2006 (as amended);

“Acquisition” means the proposed recommended acquisition by the Purchaser of the entire issued and to be issued share capital of the Company which is to be effected by means of the Scheme subject to the Scheme Terms and Conditions and any subsequent revision, variation, extension or renewal thereof;

“Acquisition Proposal” means any bona fide written offer or proposal to acquire, directly or indirectly, fifteen percent (15%) or more of (i) the consolidated assets of either (A) the Company and its Subsidiaries (taken as a whole) or (B) the Purchaser and its Subsidiaries (taken as a whole), or (ii) the equity or other voting power of either

(X) the Company or (Y) the Purchaser, in each case, whether by merger, consolidation, purchase of assets, tender offer, license or otherwise, or effect any such transaction (it being understood and agreed that, in the case of the Purchaser, open market acquisitions of Purchaser Common Stock by any Third Party shall not be deemed to be an “Acquisition Proposal”);

“A Ordinary Shares” means the A ordinary shares of 0.1 pence each in the capital of the Company;

“Business Day” means a day (excluding Saturdays and Sundays and public holidays in England and Wales or the United States) on which banks generally are open for business in London and New York for the transaction of normal banking business;

“Closing” means the date that is the later of (A) the date the Company files the Court Orders with the Registrar or (B) such later date as the parties mutually agree and to which the Court agrees;

“Closing Date” means the date on which the Closing occurs;

“Code” means the Internal Revenue Code of 1986, as amended;

“Company Board” means the board of directors of the Company from time to time;

“Company Board Recommendation” means the recommendation of the Company Board that the shareholders of the Company vote in favour of the Company Resolutions;

“Company Employee Plan” means any plan, program, policy, practice, contract, agreement or other arrangement providing for compensation, severance, termination pay, deferred compensation, performance awards, commission, bonus, stock or stock related awards, fringe benefits or other employee benefits or remuneration of any kind, whether written, unwritten or otherwise, funded or unfunded, including each “employee benefit plan,” within the meaning of Section 3(3) of ERISA and each employment benefit plan applicable to employees in the United Kingdom which is or has been maintained, contributed to, or required to be contributed to, by the Company or to any ERISA Affiliate for the benefit of any Employee, or with respect to which the Company, or any ERISA Affiliate has or may have any liability or obligation;

“Company Intellectual Property” means all Intellectual Property owned, controlled or exploited by the Company or its Subsidiaries;

“Company Irrevocable Voting Undertakings” means undertakings in the form attached at Part 1 of Schedule 4 from the shareholders listed on Schedule 6, to vote in favour of the Company Resolutions;

“Company Material Adverse Effect” means any Effect that is, or is reasonably likely to be, materially adverse to the business, assets (whether tangible or intangible) and liabilities taken together, operations or financial condition of the Company and its Subsidiaries, taken as a whole (including any adverse Effect resulting from the loss of employees); provided, however, that in no event shall any of the following, alone or in combination, be deemed to constitute, nor shall any of the following be taken into account in determining whether there has been a “Company Material Adverse Effect”: (i) any adverse Effect to the extent primarily attributable to changes or conditions

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generally affecting the industry in which the Company operates to the extent such Effect does not have a disproportionately adverse effect upon the Company in comparison to other companies in the same industry in which the Company operates; (ii) any adverse Effect primarily resulting from compliance with the terms and conditions of, or the taking of any action required by this Agreement, including the public announcement of the execution of this Agreement; (iii) any adverse Effect arising directly or indirectly from or otherwise relating directly or indirectly to general economic, business, financial, market or political conditions to the extent such Effect does not have a disproportionately adverse effect upon the Company in comparison to other companies in the same industry in which the Company operates; (iv) any adverse Effect arising directly or indirectly from or otherwise relating directly or indirectly to fluctuations in the value of the U.S. Dollar or the Great British Pound Sterling; (v) any adverse Effect arising directly or indirectly from or otherwise relating directly or indirectly to any act of terrorism, war, calamity or any other similar event; (vi) any failure of the Company to meet internal expectations or financial projections (it being understood that any occurrence or state of facts that may have caused or contributed to such failure may be taken into consideration when determining whether a Company Material Adverse Effect has occurred); or (vii) any legal proceedings made or brought by any of the current or former stockholders of the Company (on their own behalf or on behalf of the Company) against the Company or the members of the Company Board relating to, arising out of or in any way connection to this Agreement, the Acquisition or the Scheme;

“Company Meetings” means the Court Meetings and the General Meeting;

“Company Options” means all issued and outstanding options (including commitments to grant options) to purchase or otherwise acquire Shares (whether or not vested) held by any Person;

“Company Resolutions” means the General Meeting Resolutions, including the resolution to amend the articles of association of the Company in the form set out in Schedule 10 and the resolutions of the Company’s shareholders to be voted upon at the Court Meetings, in order to approve the Scheme and to approve other matters in relation to assisting the Scheme to become effective;

“Company Unvested Shares” means any Shares issued and outstanding immediately prior to the Closing that are unvested or are subject to a repurchase option, risk of forfeiture or other similar condition under any applicable stock restriction agreement or other agreement with the Company;

“Company Warrants” means all issued and outstanding warrants (including commitments to grant warrants) to purchase or otherwise acquire Shares (whether or not vested) held by any Person;

“Confidentiality Agreement” means the Confidentiality Agreement between the Company and the Purchaser dated of February 27, 2009, as amended on March 29, 2010, July 16, 2010 and August 26, 2010;

“Court” means the High Court of Justice in England and Wales;

“Court Hearings” means the hearings by the Court to sanction the Scheme under Section 899 of the 2006 Act and to confirm the associated Reduction;

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“Court Meetings” means the separate meetings (including any adjournment thereof) of holders of the Ordinary Shares, the A Ordinary Shares, the Preferred A Shares, the Preferred B Shares and the Preferred C Shares convened pursuant to an order of the Court under Section 896 of the 2006 Act for the purposes of considering and, if thought fit, approving the Scheme (with or without amendment);

“Court Orders” means the orders of the Court sanctioning the Scheme under Section 899 of the 2006 Act and confirming the associated Reduction;

“DGCL” means the Delaware General Corporation Law;

“Effect” means any event, circumstance, change or effect;

“Employee” means any current or former employee, officer, consultant or director of the Company or any ERISA Affiliate;

“End Date” means August 31, 2011, unless extended by the mutual written agreement of the parties;

“Entity” means any corporation (including any non-profit corporation), general partnership, limited partnership, limited liability partnership, joint venture, estate, trust, company (including any company limited by shares, limited liability company or joint stock company), firm, society or other enterprise, association, organization or entity (including any Governmental Entity);

“ERISA Affiliate” means each Subsidiary of the Company and any other Person currently or in the past under common control with the Company or any of its Subsidiaries within the meaning of Section 414(b), (c), (m) or (o) of the Code, and the regulations issued thereunder and as set out within sections 1161 and 1162 of the Act;

“Exchange Act” means the United States Securities Exchange Act of 1934, as amended;

“General Meeting” means the extraordinary general meeting of the Company’s shareholders to be convened in connection with the Scheme;

“General Meeting Resolutions” means the resolutions to be proposed at the General Meeting for the purposes of approving the Reduction and adopting new Articles of Association of the Company and such other matters as may be agreed between the Company and the Purchaser as necessary or desirable for the purposes of implementing the Scheme and/or the Acquisition;

“Governmental Entity” means any court, administrative agency or commission or other governmental authority, instrumentality, agency or commission;

“Group” means, in relation to any Person, any Entity of which securities or other ownership interests having ordinary voting power to elect a majority of the board of directors or other persons performing similar functions are at any time directly or indirectly owned by such Person or any subsidiary undertakings as defined in section 1162 of the Act;

“ICTA” means the Income and Corporation Taxes Act 1988;

“Initial Consideration” has the meaning set forth in the Scheme Terms and Conditions;

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“Intellectual Property” means all patents, copyrights, trademarks, service marks, trade names, prototypes, design rights, mask works, logos, rights in relation to databases, rights in relation to know-how, rights in domain names, rights protecting goodwill and reputation, rights in unfair competition and all other intellectual property rights and analogous rights as may exist anywhere in the world for the full term of the rights concerned whether registered or unregistered and including all registrations, pending registrations and applications for registration,  relating to any such rights; all reversions, extensions and renewals of such rights; and all accrued rights of action in relation to such rights (including the right to sue for and recover damages for past infringement(s));

“Legal Requirements” means laws, statutes, standard ordinances, codes, resolutions, promulgations, rules, regulations, orders, judgments, writs, injunctions, decrees, or any other similar legal requirements having the force or effect of law;

“Lock-Up Agreements” means the Purchaser Lock-Up Agreement and the Seller Lock-Up Agreement;

“Nasdaq” means the Nasdaq Stock Market;

“Options Communications” means communications sent to holders of Company Options under the Plans in accordance with Schedule 8;

“Ordinary Shares” means the ordinary shares of 0.1 pence each in the capital of the Company;

“Permitted Bonuses” means the cash bonuses that are payable to employees of the Company participating in the Company’s Share Incentive Plan (“SIP Participants”) to cover the tax liability (grossed up for the Tax liability payable with respect to the bonus payment) of the SIP Participants that results from the cancellation of the Ordinary Shares currently held subject to the terms of the Share Incentive Plan (“SIP”) following the Closing Date in consideration of the receipt by the SIP of its allocation of the Consideration under the Scheme;

“Person” means a natural person or an Entity;

“Plans” means the Astex Technology Share Option Plan for consultants adopted on 4 April 2000, the Astex Technology Limited Enterprise Management Incentive Scheme adopted on 27 March 2002 and the Astex Therapeutics Limited 2010, and “Plan” means any one of them, as the context determines or requires;

“Preferred A Shares” means, the non-cumulative convertible preferred ordinary shares (Series A) of 0.1 pence each in the capital of the Company;

“Preferred B Shares” means, the non-cumulative convertible preferred ordinary shares (Series B) of 0.1 pence each in the capital of the Company;

“Preferred C Shares” means, the non-cumulative convertible preferred ordinary shares (Series C) of 0.1 pence each in the capital of the Company;

“Press Announcement” means the draft press announcement to be issued by the Purchaser in relation to the Acquisition in the agreed form set out in Schedule 1;

“Purchaser Board” means the board of directors of the Purchaser from time to time;

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“Purchaser Board Recommendation” means the recommendation of the Purchaser Board that the stockholders of the Purchaser vote in favour of the Purchaser Resolutions;

“Purchaser Common Stock” means shares of common stock, par value $0.001 per share, of the Purchaser;

“Purchaser Intellectual Property” means all Intellectual Property owned, controlled or exploited by the Purchaser or its Subsidiaries;

“Purchaser Material Adverse Effect” means any Effect that is, or is reasonably likely to be, materially adverse to the business, assets (whether tangible or intangible) and liabilities taken together, operations or financial condition of the Purchaser and its Subsidiaries taken as a whole (including any adverse Effect resulting from the loss of employees); provided, however, that in no event shall any of the following, alone or in combination, be deemed to constitute, nor shall any of the following be taken into account in determining whether there has been a “Purchaser Material Adverse Effect”: (i) any adverse Effect to the extent primarily attributable to changes or conditions generally affecting the industry in which the Purchaser operates to the extent such Effect does not have a disproportionately adverse effect upon the Purchaser in comparison to other companies in the same industry in which the Purchaser operates; (ii) any adverse Effect primarily resulting from compliance with the terms and conditions of, or the taking of any action required by this Agreement, including the public announcement of the execution of this Agreement;  (iii) any failure by the Purchaser to meet any published securities analyst estimates of revenues or earnings for any period ending on or after the date of this Agreement and prior to the Closing Date (provided that the underlying causes of any such failures may (subject to the other provisions of this Agreement) be taken into account in making a determination as to whether there has been a Purchaser Material Adverse Effect) and (iv) any decline in the price of the Purchaser Common Stock; (v) any adverse Effect arising directly or indirectly from or otherwise relating directly or indirectly to general economic, business, financial, market or political conditions to the extent such Effect does not have a disproportionately adverse effect upon the Purchaser in comparison to other companies in the same industry in which the Purchaser operates; (vi) any adverse Effect arising directly or indirectly from or otherwise relating directly or indirectly to fluctuations in the value of the U.S. Dollar or the Great British Pound Sterling; (vii) any adverse Effect arising directly or indirectly from or otherwise relating directly or indirectly to any act of terrorism, war, calamity or any other similar event; or (viii) any legal proceedings made or brought by any of the current or former stockholders of the Purchaser (on their own behalf or on behalf of the Purchaser) against the Purchaser or the members of the Purchaser Board relating to, arising out of or in any way connection to this Agreement, the Acquisition or the Scheme.

“Purchaser Lock-Up Agreement” means the lock-up agreement in the form attached at Part 1 of Schedule 9;

“Purchaser Resolutions” means the resolutions of the Purchaser’s stockholders to be voted upon at the Purchaser Stockholder Meeting, in order to give the Requisite Purchaser Stockholder Approval;

“Purchaser Restricted Shareholders” means the holders of the Preferred A Shares, the Preferred B Shares and the Preferred C Shares;

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“Purchaser Stockholder Meeting” means the special meeting of the Purchaser’s stockholders to be convened in connection with the Acquisition to consider and, if thought fit, approve the Purchaser Resolutions;

“Purchaser Support Agreements” means agreements in the form attached at Part 2 of Schedule 4 from the stockholders set forth on Schedule 7 to vote in favour of the Purchaser Resolutions;

“Reduction” means the proposed reduction of the entire issued capital of the Company under section 645 of the Act provided for by the Scheme;

“Registrar” means the Registrar of Companies for England and Wales;

“Representatives” of a particular party to this Agreement means the directors, officers, employees, agents, advisers (including financial and legal advisers) and other representatives of such party and its Subsidiaries;

“Requisite Company Shareholder Approval” means the passing of all the Company Resolutions;

“Requisite Purchaser Stockholder Approval” means the approval of the issuance of Purchaser Common Stock as part of the Initial Consideration and the possible issuance of Purchaser Common Stock as part of the Deferred Consideration by a majority of the shares represented in person or by proxy at the Purchaser Stockholder Meeting;

“Restricted Shareholders” means the Purchaser Restricted Shareholders and the Seller Restricted Shareholders;

“Scheme” means the scheme of arrangement under Part 26 of the Act to be proposed by the Company to its shareholders, with or subject to any modification, addition or condition approved or imposed by the Court and agreed by the Company and the Purchaser pursuant to which the Acquisition is proposed to be implemented;

“Scheme Document” means the document to be despatched to the Company’s shareholders setting out the full terms of the Scheme and, where the context so admits, includes any form of proxy, election, notice or other document required to be despatched to Shareholders in connection with the Scheme reflecting and containing the Scheme Terms and Conditions, to be prepared in accordance with clause 4.2;

“Scheme Terms and Conditions” means the agreed form terms and conditions to form part of the Scheme Document contained in Schedule 2.

“Securities Act” means the United States Securities Act of 1933, as amended;

“Seller Lock-Up Agreement” means the lock-up agreement substantially in the form attached at Part 2 of Schedule 9 (with such amendments as may be agreed by representatives of Abingworth, Apax and GIMV (acting by simple majority) at any time prior to the date of issue of the Part 8 claim form under clause 4.2(a) that are necessary or desirable in their reasonable opinion to mitigate the impact of the Securities Act and other applicable U.S. Legal Requirements on the Seller Restricted Shareholders) and the exhibit thereto, provided that if such representatives of Abingworth, Apax and GIMV are unable to agree on any such amendments, then any one of them shall be entitled to require by notice in writing to the others and to the Purchaser that the Seller Lock-Up Agreement not be executed and all references to the Seller Lock-Up Agreement shall be deemed to be deleted for all purposes if such notice is given;

“Seller Restricted Shareholders” means the Persons referred to in the exhibit to the Seller Lock-Up Agreement;

“Shares” means the Ordinary Shares, the A Ordinary Shares, the Preferred A Shares, the Preferred B Shares and the Preferred C Shares;

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“Subsidiary” or “Subsidiaries” means, individually or collectively, with respect to any Entity, any Entity of which securities or other ownership interests having ordinary voting power to elect a majority of the board of directors or other Persons performing similar functions are at any time directly or indirectly owned by such Entity or subsidiary undertakings as defined in section 258 of the Act;

“Superior Offer” means an Acquisition Proposal made by a Third Party subsequent to the date of this Agreement to acquire, directly or indirectly, pursuant to a tender offer, exchange offer, merger, consolidation or other business combination, all or substantially all of the assets of, or more than 50% of the total outstanding voting securities of the Company or the Purchaser, as applicable, which (i) the Company Board or Purchaser Board, as applicable, has in good faith concluded (following consultation with its outside legal counsel), taking into account, among other things, the legal, financial, regulatory and other aspects of the offer and the Third Party making the offer, would, if timely consummated in accordance with its terms, be more favourable to the stockholders of the Company or Purchaser, as applicable, in their capacities as such, from a financial point of view than the Transactions contemplated by this Agreement and (ii) is not subject to financing contingencies (or, if financing is required, then such financing is fully committed to the Third Party making the offer);

“Taxes” means any form of tax, levy, impost, duty, charge, contribution, deduction or withholding whenever imposed, collected or assessed by, or payable to, a Tax Authority including any tax on gross or net income profit or gains, corporation tax, capital gains tax, inheritance tax, wealth taxes, value added tax, customs duties, excise duties, stamp duty, stamp duty land tax, payments under the pay as you earn regime, national insurance and other similar contributions, any liability arising under section 419, section 601, section 703 or section 747 of ICTA and any penalty, charge, cost and interest included in or relating to any of the above or to any obligation in respect of any of the above and any liability to make a payment by way of reimbursement, recharge, indemnity, damages or management charge connected in any way with any taxation (in all cases, regardless of whether such taxes, duties, levies, charges, imposts, withholdings, penalties, charges, costs and interest are directly or primarily chargeable against, recoverable from or attributable to the Company or any other Person and regardless of whether the Company has, or may have, any right of reimbursement against any other Person);

“Tax Authority” means any government, state or municipality or any local, state, federal or other fiscal, revenue, customs or excise authority, body or official in the United Kingdom or elsewhere with the responsibility

“Termination Fee Amount” means the sum of $6,000,000 (six million United States Dollars);

“Third Party” means any Person or Group, who is not a party to this Agreement;

“Timetable” means the proposed indicative timetable in the agreed form for implementation of the Scheme set out in Schedule 3;

“Transactions” means the transactions contemplated by this Agreement, including the Acquisition; and

“Transaction Agreements” means the Scheme Document (including any exhibits, schedules and appendices thereto), this Agreement, the Irrevocable Voting Undertakings, the Purchaser Support Agreements and the Lock-Up Agreements.

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2.                                      INTERPRETATION

2.1                                 References to clauses and schedules are to clauses of, and schedules to, this Agreement.  The exhibits and schedules to this Agreement form a part of, and are incorporated into, this Agreement.

2.2                                 References to one gender include all genders and references to the singular include the plural and vice versa.

2.3                                 Any word or expression defined in the Act and not expressly defined in this Agreement or in the Scheme Document shall have the meaning given in the Act.

2.4                                 A reference to any statute or statutory provision shall be construed as a reference to the same as it may have been, or may from time to time be, amended, modified or re- enacted.

2.5                                 Any reference to a time of day is a reference to the time in London, unless a contrary indication appears. Any reference to a “day” (including within the phrase “Business Day”) means a period of 24 hours running from midnight to midnight.

2.6                                 A document “in the agreed form” means a document, the terms of which have been approved by the parties and a copy of which has been identified as such and initialled by or on behalf of each of the Company and the Purchaser.

2.7                                 A reference to any other document referred to in this Agreement is a reference to that other document as amended, revised, varied, novated or supplemented at any time.

2.8                                 Any reference to a party means any party to this Agreement and their successors in title.

2.9                                 The parties hereto agree that they have been represented by counsel during the negotiation, preparation and execution of this Agreement and, therefore, waive the application of any law, regulation, holding or rule of construction providing that ambiguities in an agreement or other document will be construed against the party drafting such agreement or document.

2.10                           The words “include,” “includes” and “including” when used herein shall be deemed in each case to be followed by the words “without limitation.”

2.11                           All references to “$,” or “dollars” refer to the lawful currency of the United States.  All references to “£,” “pounds,” “sterling,” or “pounds sterling” refer to the lawful currency of the United Kingdom.

2.12                           Headings are to be ignored in construing this Agreement.

3.                                      PRESS ANNOUNCEMENT

The Purchaser shall release the Press Announcement at or before 8:00 am Eastern Standard Time, USA, on April [6] 2011 or such other time and date as may be agreed in writing by the parties.

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4.                                      IMPLEMENTATION AND DOCUMENTATION

Implementation of the Scheme

4.1                                 Save as set out in this Agreement, the parties undertake to implement the Scheme in accordance with, and subject to the Scheme Terms and Conditions and, so far as reasonably practicable, the Timetable, with the overall intention that the Scheme becomes effective on or before the End Date, but in any event, in as timely manner as reasonably practicable.

(a)                                  The parties agree to each work diligently with a view to finalising the Scheme Document and the Options Communications, with the Company and its advisers taking the lead in such preparation, as soon as reasonably practicable after the date of this Agreement. The Company shall not post the Scheme Document to its shareholders without the prior written consent of the Purchaser. The Company undertakes to the Purchaser that the Scheme Document will reflect and incorporate the Scheme Terms and Conditions.

4.2                                 The Company will, save as otherwise agreed in writing with the Purchaser, take or cause to be taken all such steps as are necessary to implement the Scheme in accordance with, so far as is reasonably practicable, the Timetable, and the Purchaser will, save as otherwise agreed in writing with the Company, take or cause to be taken all such steps as are requested by the Company and necessary to assist the Company in implementing the Scheme in accordance with, so far as is reasonably practicable, the Timetable. In particular, but without limitation:

(a)                                  the Company shall make all necessary applications to the Court in connection with the implementation of the Scheme promptly and in particular, will, in accordance with, in so far as reasonably practicable, the Timetable, issue a Part 8 claim form in order to seek the Court’s permission to convene the Court Meetings and file such documents as may be necessary in connection therewith;

(b)                                 upon:

(i)                                     the necessary documents being settled with the Court and, where required, approved by the Purchaser; and

(ii)                                  the Court making the order necessary for the purpose of convening the Court Meetings,

the Company shall, as promptly as practicable following the order being made, publish the requisite documents, including the Scheme Document and the Options Communications, and thereafter as promptly as practicable, publish and/or post such other documents and information as the Court may approve or require from time to time in connection with the proper implementation of the Scheme according to, so far as reasonably practicable, the Timetable;

(c)                                  the Company will convene the Court Meetings and the General Meeting to take place on the same date and promptly following the Court Meetings to consider and, if thought fit, approve the Scheme and General Meeting Resolutions and hold such meetings at the times and dates on which they are convened;

(d)           keep the Purchaser informed on a regular basis of the number of proxy votes received in respect of the Company Resolutions to be proposed at the Company Meetings and the identity of the relevant shareholders;

(e)                                  following the Court Meetings and the General Meeting, and assuming the Company Resolutions to be proposed at such meetings have been passed by

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the requisite majorities, the Company shall, following receipt of the Requisite Purchaser Stockholder Approval, forthwith seek the sanction of the Court to the Scheme and confirmation of the Reduction by the Court at the Court Hearings and take all other action necessary to make the Scheme effective;

(f)                                    subject to clause 4.4, as soon as practicable after the sanction by the Court of the Scheme and the confirmation of the Reduction at the Court Hearings, and in any event within one Business Day following the Court’s confirmation of the Reduction, the Company shall cause an office copy of the Court Orders to be filed with the Registrar; and

(g)                                 notwithstanding anything to the contrary contained in this Agreement, but subject to the Company’s right to terminate this Agreement pursuant to clause 9.1 of this Agreement, the obligation of the Company to call, give notice of, convene and hold the Company Meetings and to seek the Requisite Company Shareholder Approval shall not be limited to or otherwise affected by the commencement, disclosure, announcement or submission to it of any Acquisition Proposal or by any change of the Company Board Recommendation.

4.3                                 The Company undertakes:

(a)                                  to procure the publication of the advertisements required by the Court;

(b)                                 prior to the Court Meetings and the General Meeting to keep the Purchaser informed in writing, on a weekly basis and daily on each of the five Business Days preceding each of the Court Meetings and the General Meeting (or adjournment of any of these Meetings), of the number of proxy votes received in respect of the Company Resolutions to be passed at the Court Meetings or the General Meeting as applicable;

(c)                                  promptly to provide the Purchaser with a copy of the Court Orders once obtained; and

(d)                                 to take all reasonable steps to preserve the availability of the exemption from registration provided by Section 3(a)(10) of the Securities Act, including:

(i)                                     conducting a hearing on the fairness of the Scheme to the Scheme Shareholders;

(ii)                                  advising the Court before the hearing on the fairness of the Scheme that, if the terms and conditions of the Scheme are approved, its sanctioning of the Scheme will constitute the basis for the Purchaser Common Stock offered pursuant to the Scheme to be issued without registration under the Securities Act in reliance on the exemption from registration provided by Section 3(a)(10); and

(iii)                            providing adequate notice of the hearing and an opportunity to attend the hearing and be heard to all Persons to whom shares of Purchaser Common Stock are proposed to be issued pursuant to the Scheme.

4.4                                 The Company agrees that it shall only (i) seek the sanction of the Court to the Scheme at the Court Hearings and/or (ii) file the Court Orders with the Registrar if the Purchaser provides written confirmation that all of the Conditions, where capable of satisfaction, have been satisfied or, where permissible, waived by the Purchaser.

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4.5                                 The Company shall not amend or seek to amend the Scheme or the General Meeting Resolutions after despatch of the Scheme Document or to adjourn the Court Meetings or the General Meeting without the prior written consent of the Purchaser.

4.6                                 The Purchaser will undertake to the Court to be bound by the terms of the Scheme, including as to the discharge of the consideration for the Acquisition, and shall cause the shares of Purchaser Common Stock to be issued in connection with the Acquisition to be approved for listing on Nasdaq, subject to official notice of issuance, as promptly as practicable after the date hereof, and in any event, prior to the Closing Date.

4.7                                 Save as may otherwise be agreed between them, the parties shall use all reasonable endeavours to ensure that the time period between the posting of the Scheme Document and the Closing Date is as short as reasonably possible.

Recommendation and responsibility

4.8                                 Subject to the provisions of clause 8:

(a)                                  the Company agrees that (i) the Scheme Document shall incorporate an unqualified recommendation of the Company Board to shareholders of the Company to vote in favour of the Company Resolutions and (ii) such recommendation shall not be withdrawn or qualified save (in the case of both (i) and (ii)) to the extent that the Company Board has determined to change its recommendation in accordance with clause 8.4; and

(b)                                 the Purchaser agrees that (i) the Proxy Statement shall incorporate the recommendation of the Purchaser Board to stockholders of the Purchaser to vote in favour of the Purchaser Resolutions; and (ii) such recommendation shall not be withdrawn or qualified save (in the case of both (i) and (ii)) to the extent that the Purchaser Board has determined to change its recommendation in accordance with clause 8.8.  Without limiting the provisions of clause 8.8, nothing in this clause 4.8 shall prohibit the Purchaser or the Purchaser Board from taking and disclosing to its stockholders a position, or any information, with respect to an Acquisition Proposal by a Third Party to the extent required under applicable law (including Rule 14d-9 and Rule 14e-2 promulgated under the Exchange Act) or stock exchange regulation.

Co-operation

4.9                                 Each party agrees to use all reasonable endeavours to, and to procure that its Group, its directors and its relevant professional advisers assist it to, prepare all such documents and take all such steps as are reasonably necessary or desirable in connection with the Scheme and the Acquisition.

4.10                           Each party will co-operate with and provide the other with such information relating to it and its Group and such access to the officers, directors and senior management of the other as reasonably required during normal business hours in order to facilitate and assist with planning for the integration of the Company and the Purchaser.  No information or knowledge known to the Purchaser or the Company or any of their Representatives (whether prior to or after the date of this Agreement) and no information or knowledge obtained in any investigation pursuant to this clause 4.10 (or otherwise) shall affect or be deemed to modify any representation or warranty contained herein or the conditions to the obligations of the parties to consummate the Acquisition in accordance with the provisions hereof.

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4.11         Should any supplemental circular or announcement be required to be published or submitted to the Court in connection with the Acquisition (a “Supplemental Document”) each party shall provide such co-operation and information (including such information as is necessary for the Supplemental Document to comply with all applicable legal and regulatory provisions) as the other may reasonably request and is reasonably necessary to finalise and publish promptly such Supplemental Document.

4.12         The Purchaser and the Company shall promptly execute and file, or join in the execution and filing of, any application, notification or other document that may be necessary in order to obtain the authorization, approval or consent of any Governmental Entity, which may be reasonably required, or which either party may reasonably request, in connection with the consummation of the Transactions.  The Purchaser and the Company shall use commercially reasonable efforts to obtain all such authorizations, approvals and consents.  Each of the Purchaser and the Company shall promptly inform the other of any material communication between the Company or the Purchaser, as applicable, and any Governmental Entity regarding the Acquisition or any other Transactions.  If the Company or the Purchaser or any affiliate thereof shall receive any formal or informal request for information or documentary material from any Governmental Entity with respect to the Acquisition or any other Transactions, then the Company or the Purchaser (as applicable) shall make, or cause to be made, as soon as reasonably practicable, a response in compliance with such request.  Each of the Company and the Purchaser shall direct, in its sole discretion, the making of such response, but shall consider in good faith the views of the other.  Notwithstanding the foregoing or anything to the contrary set forth in this Agreement, neither the Purchaser nor the Company shall be required to agree to any divestiture by the Purchaser or the Company, as the case may be, or any of the Purchaser’s or the Company’s Subsidiaries or affiliates, of shares of capital stock or of any business, assets or property of the Purchaser or the Company or any of the Purchaser’s or the Company’s Subsidiaries or affiliates or the imposition of any material limitation on the ability of any of them to conduct their businesses or to own or exercise control of such assets, properties and stock and the Company and its Subsidiaries shall not agree to take such actions without the prior written consent of the Purchaser.

Proxy Statement; Regulation M-A

4.13         As promptly as practicable after the execution and delivery of this Agreement, the Purchaser shall prepare and shall file with the United States Securities and Exchange Commission (the “SEC”) a proxy statement of the Purchaser for use in connection with the solicitation of proxies for the Requisite Purchaser Stockholder Approval and (B) such other matters as may be necessary or proper for consideration at the Purchaser Stockholder Meeting (the “Purchaser Voting Proposals”) in connection with the Transactions (as may be amended or supplemented from time to time, the “Proxy Statement”).

The Purchaser shall provide the Company with a reasonable opportunity to review and comment on the Proxy Statement and all amendments and supplements thereto, and the Purchaser shall include all additions, deletions or changes thereto suggested by the Company and its legal counsel unless the Purchaser determines, in its good faith discretion, that such additions, deletions or changes are not appropriate.  Each of the Purchaser and the Company shall use its reasonable best efforts to have the Proxy Statement cleared of SEC comments as promptly as practicable after such filing with the SEC.  Without limiting the generality of the foregoing, each of the Company and the Purchaser shall, and shall cause its respective Representatives to, fully cooperate with the other party hereto and its respective Representatives in the preparation of the Proxy Statement and shall furnish the other party hereto with all information concerning

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it and its affiliates as the other party hereto may deem reasonably necessary or advisable in connection with the preparation of the Proxy Statement, and any amendments or supplements thereto.  As promptly as practicable after the preliminary Proxy Statement is cleared of any and all SEC comments, as applicable, the Purchaser shall cause the Proxy Statement to be mailed to its stockholders.

4.14         From and after the date hereof, the Company shall deliver to the Purchaser the Specified GAAP Financials required under clause 4.18 of this Agreement in order to comply with the SEC rules and regulations for the Proxy Statement.

4.15         The Purchaser shall cause the Proxy Statement to comply in all material respects as to form and substance with the requirements of the Securities Act, the Exchange Act and the DGCL.  Without limiting the generality of the foregoing, the information supplied or to be supplied by or on behalf of either party hereto for inclusion in any filing pursuant to Rule 165 and Rule 425 under the Securities Act or Rule 14a-12 under the Exchange Act (each, a “Regulation M-A Filing”) shall not, at the time any such Regulation M-A Filing is filed with the SEC, contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading.  Without limiting the generality of the foregoing, prior to the Closing, (i) the Company and the Purchaser shall notify each other as promptly as practicable upon becoming aware of any event or circumstance which should be described in an amendment of, or supplement to, the Proxy Statement or any Regulation M-A Filing so that any such document would not include any misstatement of material fact or omit to state any material fact necessary to make the statements therein, in light of the circumstances under which they are made, not misleading, and as promptly as practicable thereafter, the Purchaser shall cause an appropriate amendment or supplement describing such information to be promptly filed with the SEC and, to the extent required by applicable Legal Requirements or the SEC, disseminated to the stockholders of the Purchaser.  The Company and the Purchaser shall each notify the other as promptly as practicable after the receipt by it of any written or oral comments of the SEC or its staff on, or of any written or oral request by the SEC or its staff for amendments or supplements to, the Proxy Statement or any Regulation M-A Filing, and shall promptly supply the other with copies of all correspondence between it or any of its Representatives and the SEC or its staff with respect to any of the foregoing filings.  The Purchaser shall respond promptly to any comments received from the SEC or its staff with respect to the Proxy Statement or any Regulation M-A Filing, and shall correct promptly any information or statements therein if and to the extent that it becomes aware that such information shall be or shall have become false or misleading in any material respect.

Purchaser Stockholder Meeting

4.16         Subject to the Purchaser’s rights to terminate this Agreement in accordance with the terms of clause 9.1, as promptly as possible after the date on which the preliminary Proxy Statement is cleared of all SEC comments, the Purchaser shall duly call, give notice of, convene and hold the Purchaser Stockholder Meeting for the purpose of considering and voting upon the approval of the Purchaser Voting Proposals.  Subject to the Purchaser’s rights to terminate this Agreement in accordance with the terms of clause 9.1 and subject to clause 4.17, the Purchaser shall solicit from its stockholders proxies in favour of the Purchaser Voting Proposals, and shall use its reasonable best efforts to secure the Requisite Purchaser Stockholder Approval.  The Purchaser shall solicit all proxies in connection with the Purchaser Stockholder Meeting in compliance with the DGCL, the rules of the Nasdaq, the Purchaser’s certificate of incorporation and the Purchaser’s bylaws and all other applicable Legal Requirements.

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4.17         Notwithstanding anything to the contrary set forth in this Agreement, the Purchaser, after consultation with the Company, shall adjourn or postpone the Purchaser Stockholder Meeting (i) to the extent required by the SEC or the 1934 Act if any required supplement or amendment to the Proxy Statement shall have been provided to the Purchaser Stockholders, or (ii) if as of the time for which the Purchaser Stockholder Meeting is originally scheduled (as set forth in the Proxy Statement), there are insufficient shares of Purchaser Common Stock represented (either in person or by proxy) at the Purchaser Stockholder Meeting to constitute a quorum necessary to conduct the business of the Purchaser Stockholder Meeting.

Financial Statements

4.18         As soon as practicable following the date of this Agreement, but in any event at least three (3) Business Days prior to the Closing Date, the Company shall prepare and deliver to the Purchaser the Company’s audited balance sheets, statements of income, statement of comprehensive income and statements of cash flows, prepared in accordance with IFRS, for the years ended December 31, 2009 and December 31, 2010 (which shall include pro-forma financial statements with a reconciliation to U.S. generally accepted auditing principles for the year ended December 31, 2010 (collectively, the “Specified IFRS Financials”)).  Additionally, the Company shall contact its auditors and require that such auditors agree to provide their consent for Purchaser to use in connection with including the Specified IFRS Financials with its SEC filings.

4.19         In addition, the Company shall prepare and deliver to the Purchaser (i)  the Company’s unaudited consolidated balance sheet (the “Closing Balance Sheet”) dated as of not less than three (3) Business Days prior to the Closing Date (the “Closing Balance Sheet Date”), and the related unaudited consolidated statement of income, cash flow and shareholders’ equity for the period beginning on January 1, 2011 and ending on the Closing Balance Sheet Date (the “Closing Date Financials” and together with the Specified GAAP Financials, the “Closing Financials”).  The Company agrees that when delivered, the Closing Financials: (i) will have been prepared in accordance with IFRS (except that unaudited financial statements may not have notes thereto and other presentation items that may be required by IFRS and are subject to normal and recurring year-end adjustments that are not reasonably expected to be material in amount) applied on a consistent basis throughout the periods indicated and (ii) will fairly present in all material respects the financial condition and operating results of the Company as of the dates and for the periods indicated therein.

Governance Matters

4.20         Prior to Closing, the Purchaser shall take such actions as are necessary to increase the size of the Purchaser Board from five (5) directors to nine (9) directors and immediately following the Closing, the Purchaser shall fill the four newly created directorships with four (4) representatives nominated by the Company.  The selection of the Company-nominated directors is subject to (a) the determination by the Nominating and Governance Committee of the Purchaser Board (the “Governance Committee”) that each of the nominated representatives meets the qualifications of the Purchaser for service on the Purchaser Board and (b) the Governance Committee’s conclusion that the addition of such proposed Purchaser Board members would not cause fewer than a majority of the resulting Purchaser Board to qualify as “independent” under the rules and regulations of the SEC and Nasdaq.  If the Governance Committee determines that any of the Company nominated representatives is not qualified to serve on the Purchaser Board (which determination must be made, if at all, at least ten (10) Business Days prior to the Closing, then the

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Governance Committee shall notify the Company providing the reasons for such conclusion and the Company shall have the right to nominate replacement representatives to serve on the Purchaser Board.  As of the date of this Agreement, the Company has nominated Harren Jhoti, Peter Fellner, Ismail Kola and Tim Haines (or an alternative representative of Abingworth Management Limited to be designated prior to Closing) to be the Company nominees to serve on the Purchaser Board.  The corporate governance structure to be put in place would be to the reasonable satisfaction of the nine-member Purchaser Board, and would include the appointment of Peter Fellner as the Vice Chairman and  the appointment of Harren Jhoti as the President of the Purchaser.  In addition, the Purchaser Board will reconstitute its committees as follows:  (i) the Audit Committee will be made up of Charles Casamento (as Chairman), Thomas Girardi and Walter Lack; (ii) the Compensation Committee will  be made up of Walter Lack (as Chairman), Thomas Girardi and Tim Haines (or an alternative representative of Abingworth Management Limited); and (iii) the Governance Committee will be made up of Charles Casamento, Peter Fellner, Thomas Girardi, Allan Goldberg, Tim Haines, Ismail Kola and Walter Lack (as Chairman).  The current Pharmaceutical Committee of the Purchaser Board will be disbanded.

4.21         [Reserved]

No Solicitation

4.22         Until the earlier of  the Closing Date and the date of the valid termination of this Agreement pursuant to the provisions of clause 9.1 and subject to any scheduled exception to either clause 5.1(p) or clause 5.2(k), as the case may be, each party agrees that it shall not (nor will it permit any of its officers, directors, agents, representatives or affiliates (and, in the case of the Company, the shareholders set forth on Schedule 6) to), directly or indirectly (including, in the case of the Company, by acting through or encouraging actions by Company shareholders who are not bound by this clause), take any of the following actions with any Third Party other than the other party and its designees:  (i) solicit, seek, knowingly encourage or initiate any inquiry, negotiations or discussions, or enter into any agreement, with respect to any Acquisition Proposal (ii) disclose any information not customarily disclosed to any Person concerning its (or any of its Subsidiary’s) business, technologies or properties, or afford to any Person access to their respective properties, technologies, books or records, not customarily afforded such access, (iii) assist or cooperate with any Third Party to make any Acquisition Proposal.  Each party shall immediately cease and cause to be terminated any such negotiations, discussions or agreements (other than with the other party) that are the subject matter of clause (i), (ii) or (iii) of this clause 4.22 at the date of this Agreement.  Each party agrees that in the event that it or any of its affiliates shall receive, prior to the Closing Date or the valid termination of this Agreement in accordance with clause 9.1, any offer, proposal, or request concerning an Acquisition Proposal, or any request for disclosure or access as referenced in clause (ii) above, it shall promptly notify the other party thereof, including information as to the identity of the offeror or the party making any such offer or proposal and the specific terms of such offer or proposal, as the case may be, and such other information related thereto as the other party may reasonably request.  The parties hereto agree that irreparable damage would occur in the event that the provisions of this clause 4.22 were not performed in accordance with their specific terms or were otherwise breached.  It is accordingly agreed by the parties hereto that a party shall be entitled to an immediate injunction or injunctions, without the necessity of proving the inadequacy of money damages as a remedy and without the necessity of posting any bond or other security, to prevent breaches of the provisions of this clause 4.22 and to enforce specifically the terms and provisions hereof in any court of the United States or

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any state having jurisdiction, this being in addition to any other remedy to which such party may be entitled at law or in equity.

Notification of Certain Matters

4.23         Each of the Purchaser, on the one hand, and the Company, on the other hand, shall give prompt notice to the other party hereto of:  (a) the occurrence or non occurrence of any event, the occurrence or non occurrence of which is likely to cause any representation or warranty of such party contained in Schedule 5 of this Agreement to be untrue or inaccurate in any material respect at or prior to the Closing Date, such that the Closing condition set forth in clause 6.2(a) (in the case of the Purchaser) or clause 6.3(a) (in the case of the Company) would not be satisfied; (b) any failure of such party to comply with, in any material respect, any covenant or agreement to be complied with by it hereunder, such that the Closing condition set forth in clause 6.2(b) (in the case of the Purchaser) or clause 6.3(b) (in the case of the Company) would not be satisfied; (c) any event involving the Purchaser or its Subsidiaries, on the one hand, or the Company and its Subsidiaries on the other hand, that has resulted in a Purchaser Material Adverse Effect or a Company Material Adverse Effect, as applicable and (d) the occurrence of any material adverse change in respect of any of the Partnered Projects (as defined in the Scheme Terms and Conditions), including the occurrence of any significant adverse event of which the Company is aware in any pending clinical trials and any decision of which the Company is aware by any of the partners in any of the Partnered Projects to terminate any of the projects that are the subject matter of the Partnered Projects; provided, however, that the delivery of any notice pursuant to this clause 4.23 shall not (i) limit or otherwise affect any remedies available to the party receiving such notice or (ii) constitute an acknowledgment or admission of a breach of this Agreement or (iii) in the case of any notice under clause (d) be determinative of whether there has been a Company Material Adverse Effect.  No disclosure pursuant to this clause 4.23, however, shall be deemed to amend or supplement any representation or warranty, or prevent or cure any misrepresentations, breach of warranty or breach of covenant.

Directors’ and Officers’ Indemnification and Insurance

4.24         For a period of six (6) years following the Closing Date, the Purchaser shall, and shall cause the Company and its Subsidiaries to, fulfill and honor in all respects the obligations of the Company and its Subsidiaries pursuant to (i) each indemnification agreement in effect between the Company or any of its Subsidiaries and any Indemnified Person, and (ii) any indemnification, expense advancement and exculpation provision set forth in the organizational documents of the Company or any of its Subsidiaries as in effect on the date of this Agreement.  In addition, for a period of six (6) years following the Closing Date, the organizational documents of the Company following completion of the Scheme shall contain reasonable and customary provisions with respect to indemnification, expense, advancement and exculpation from liability, and such provisions shall not be amended, repealed or otherwise modified in any manner that could adversely affect the rights thereunder of any Indemnified Person.

4.25         Notwithstanding anything to the contrary contained elsewhere in this Agreement, the Company may obtain a prepaid tail policy (the “Tail Policy”) prior to the Closing Date, which provides the Indemnified Persons with directors’ and officers’ liability insurance for a period ending no earlier than the sixth anniversary of the Closing Date.

4.26         For purposes of this Agreement, each individual who is or was an officer or director of the Company or any of its Subsidiaries at or at or at any time prior to the Closing shall be deemed to be an “Indemnified Person.”  Notwithstanding anything to the contrary

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in this Agreement, the Indemnified Persons shall be third party beneficiaries of the provisions of clauses 4.24, 4.25 and 4.26 of this Agreement.

Purchaser Name Change

4.27         Following the Closing, Purchaser shall use its commercially reasonable efforts to effect a name change from “SuperGen, Inc.” to “Astex Pharmaceutical, Inc.” through a short-form merger under Section 253 of the applicable Delaware law (the “Name Change Merger”).  In connection with the Name Change Merger, the Purchaser shall be permitted to take all actions necessary to effect the Name Change Merger.  Without limiting the foregoing, Purchaser shall be permitted to:  (i) execute and deliver a certificate of ownership and merger or other appropriate transaction document to effect the Name Change Merger, and consummate the transactions contemplated therein, (ii) file and record all such other filings, authorizations declaration, registrations with, or notice to, or authorization, consent or approval of, any Governmental Entity as are necessary in connection with the Name Change Merger, and (iii) enter into other agreements and instruments, containing provisions that are appropriate or customary for public companies, including indemnification agreements for officers and directors.  Prior to the Closing, the Company agrees to take all actions necessary to facilitate the proposed name change, including, without limitation, reserving the name “Astex Pharmaceuticals, Inc.” in the states of Delaware and California, reserving the ticker symbol “ASTX” with Nasdaq and preparing for the transfer, as necessary, of such name and symbol.

Section 16 Matters

4.28         Purchaser shall take all steps reasonably necessary to cause the acquisition of New SuperGen Shares or other equity securities (including stock options or other derivative securities) of the Purchaser in connection with the Acquisition by each director or officer of the Company functioning as a director or officer of the Purchaser following the Acquisition to be exempt pursuant to Rule 16b-3 under the Exchange Act.

Post-Signing Irrevocable Voting Undertakings

4.29         Following the execution of this Agreement, the Company shall use commercially reasonable efforts to cause the holders of Preferred Stock (other than those set forth on Schedule 6 who shall have already executed Irrevocable Voting Undertakings) to execute and deliver to SuperGen copies of the Irrevocable Voting Undertakings in the form attached at Part 1 to Schedule 4 to this Agreement as soon as reasonably practicable after the posting of the Scheme Document.

Post-Signing Permitted Bonuses

4.30         Following the Closing Date SuperGen shall cause the Company to pay the SIP Participants the Permitted Bonuses no later than two Business Days prior to the date on which SIP Participants are obliged to remit any tax payments arising from the cancellation of the Ordinary Shares currently held subject to the terms of the SIP.

Delivery of Payment Schedule

4.31         As soon as reasonably practicable, but in any event no later than five (5) Business Days prior to the Closing, the Company will deliver to the Purchaser a draft Payment Schedule (as defined in Section 6.3(e)) setting forth an estimate of the consideration allocation among the Scheme Shareholders.  The Payment Schedule shall set forth percentages of consideration applicable to each Scheme Shareholder and shall be in a

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format reasonably acceptable to the Purchaser.  The parties agree to work in good faith to create a mutually acceptable format of Payment Schedule.  The final Payment Schedule shall be delivered by the Company no later than one (1) Business Day prior to the Closing.

5.             CONDUCT OF BUSINESS

5.1           During the period from the date of this Agreement and continuing until the earlier of the termination of this Agreement or the Closing, the Company shall (save with the prior written consent of the Purchaser, such consent not to be unreasonably withheld): (a) carry on the Company’s and its Subsidiaries’ business in the usual, regular and ordinary course in substantially the same manner as conducted prior to the date of this Agreement and (b) use commercially reasonable efforts to (i) pay its debts and Taxes when due (except for Taxes being contested in good faith by appropriate proceedings diligently pursued and for which adequate reserves have been made), and (ii) to the extent consistent with past practice and policies, preserve intact the Company’s present business organisation, keep available the services of present officers and other key Employees (other than as contemplated in this Agreement) and preserve relationships with customers, suppliers, distributors, licensors, licensees, and others having business dealings with it, all with the goal of preserving unimpaired the Company’s and its Subsidiaries good will and ongoing businesses at the Closing Date.  Without limiting the generality of the foregoing, except as expressly contemplated by this Agreement, the Company and its Subsidiaries shall not, without the prior written consent of the Purchaser (such consent not to be unreasonably withheld):

(a)           issue, deliver, sell, allot, purchase, authorize or designate (including by certificate of designation or otherwise) or pledge or otherwise encumber or propose any of the foregoing with respect to any shares of capital stock, equity interests or other interests of the Company or any of its Subsidiaries or any securities convertible into shares of capital stock, equity or other interests of the Company or any of its Subsidiaries, or subscriptions, rights, warrants or options to acquire any shares of capital stock, equity or other interests of the Company or any of its Subsidiaries or any securities convertible into shares of capital stock, equity or other interests of the Company or any of its Subsidiaries, or enter into other agreements or commitments of any character obligating it to issue any such shares or convertible securities, other than (i) the issuance, delivery or sale of shares of capital stock, equity or other interests of the Company pursuant to the exercise of Company Options outstanding as of the date of this Agreement, and (ii) as part of the usual annual performance review process for directors, employees and officers of the Company;

(b)           purchase, redeem or otherwise acquire, directly or indirectly, any shares of capital stock, equity or other interests of the Company or any of its Subsidiaries, or otherwise reduce its authorized or issued share capital or capitalize, repay or make any other form of distribution of any amount standing to the credit of any reserve or making any other re-organization of share capital except repurchases of Company Unvested Shares at or below cost in connection with the termination of the employment relationship with any Employee pursuant to stock option or purchase agreements in effect on the date of this Agreement, provided, however, that no such repurchase shall be permitted in the event the per share repurchase price is greater than the amount of per share consideration payable for such share under the terms of this Agreement;

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(c)           waive any stock repurchase rights, accelerate, amend or change the period of exercisability or vesting of any Company Options or other rights granted under any Plan or the vesting of the securities purchased or purchasable under such Company Options or other rights or the vesting schedule or repurchase rights applicable to any Company Unvested Shares;

(d)           amend or change any other terms of Company Options or Company Unvested Shares or other rights granted under any Plan;

(e)           declare, set aside or pay any dividends on or make any other distributions (whether in cash, stock, equity securities or property) in respect of any Shares or split, combine or reclassify any Shares or issue or authorize the issuance of any other securities in respect of, in lieu of or in substitution for any Shares;

(f)            transfer or license to any Third Party or otherwise extend, amend or modify any rights to the Company Intellectual Property, or enter into grants to transfer or license to any Third Party future rights to the Company Intellectual Property, or transfer or license from any Third Party any Intellectual Property, other than (i) in the ordinary course of business consistent with past practice or (ii) pursuant to the provisions of any transfer or license entered into prior to the date of this Agreement;

(g)           enter into any contract outside the ordinary course of business (i) limiting the right of the Company to (A) engage in any line of business that is material from the standpoint of the Company’s business, operations or financial condition or (B) compete with any Third Party in any such line of business, or (ii) providing for unlimited indemnification;

(h)           (i) sell, lease, license, encumber or otherwise dispose of any tangible properties or tangible assets except sales of inventory in the ordinary course of business consistent with past practice, and except for the sale, lease, licensing, encumbering or disposition of property or assets not in excess of $100,000 individually or $1,000,000 in the aggregate, provided such property or assets are not material, individually or in the aggregate, to the business or prospects of the Company and its Subsidiaries taken as a whole, or (ii) enter into any agreement for the purchase or sale of any interest in real property, grant any security interest in any real property, enter into any lease, sublease, license or other occupancy agreement with respect to any real property or alter, amend, modify, knowingly violate or terminate any of the material terms of any of the Company’s leases;

(i)            (i) enter into or amend any contract pursuant to which any other party is granted exclusive rights or “most favored party” rights of any type or scope with respect to any of the Company products, Company Intellectual Property or its business, or containing any non-competition covenants or other material restrictions relating to its or the Purchaser’s business activities or the effect of which would be to grant to a Third Party following the Closing Date the actual or potential right to license any Purchaser Intellectual Property (other than, with respect to Subsidiaries, the Company) or (ii) enter into, amend or terminate any other contract described in the representation included as Section 1.17 of the Company’s representations and warranties in Schedule 5;

(j)            make any loan, advance (other than business expense advances to Employees in the ordinary course of business consistent with past practice) or capital contribution to, or investment in, any Third Party, incur any indebtedness or

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guarantee, issue or sell any debt securities or options, warrants, calls or other rights to acquire any debt securities of the Company, enter into any “keep well” or other agreement to maintain any financial statement condition, forgive or discharge in whole or in part any outstanding loans for borrowed money, modify any loan for borrowed money previously granted, enter into any hedging agreement or other financial agreement or arrangement designed to protect the Company or its Subsidiaries against fluctuations in commodities prices or exchange rates, or enter into any arrangement having the economic effect of any of the foregoing, in each case, other than in connection with the financing of ordinary course trade payables consistent with past practice;

(k)           grant or pay, or enter into any agreement, arrangement or amendment to an existing agreement or arrangement providing for the granting or paying of, any severance or termination pay (whether in cash, stock, equity securities, or property) or the acceleration of vesting or other benefits to any Employee except pursuant to written agreements, policies or plans outstanding on the date hereof, or adopt any new severance or termination plan, program or arrangement, or amend or modify or alter in any manner any severance or termination plan, agreement or arrangement existing on the date hereof (including any retention, change of control or similar agreement), or grant any equity-based compensation, whether payable in cash or stock, other than as part of the usual annual performance review process for directors, employees and officers of the Company;

(l)            adopt, terminate or amend any Company Employee Plan or enter into any Company Employee Plan, or adopt or amend any compensation, bonus, commission, insurance coverage (except as contemplated by this Agreement), benefit, entitlement, grant or award provided or made under any Company Employee Plan; or enter into any collective bargaining agreement; pay any special bonus, commission or special remuneration to any Employee (cash, equity or otherwise); increase the salaries, bonuses, commissions or wage rates or fringe benefits (including rights to severance or indemnification) of its Employees except as part of the Company’s usual and customary annual performance review process and consistent with past practices and except for the Permitted Bonuses; pay any benefit not provided for as of the date of this Agreement under any Company Employee Plan;

(m)          increase the size of the Company Board;

(n)       (i) hire any officers or employees (except for consultants and independent contractors retained for periods not greater than 6 months and without individual obligations of greater than $25,000 over such period) or enter into, or amend or extend the term of, any employment or consulting agreement with any Employee, or (ii) terminate any Employee (except for termination for cause), or take any action that would allow any Employee to claim a constructive termination or termination for “good reason”;

(o)       commence or settle any threatened or pending litigation;

(p)       create, extend, grant or issue any mortgage, charge, debenture or other security or permit any lien to arise on any of its assets other than in the ordinary course of business;

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(q)                     acquire any other business (including by acquiring shares or other equity interests in or the assets of any other Person) or participate in any joint venture;

(r)                        except as required by this Agreement or as otherwise deemed advisable by the Company Board to comply with any law, rule, regulation or similar requirement, cause or permit any amendments to the Articles of Association or other charter or similar documents of the Company or any of its Subsidiaries;

(s)                      change any election in respect of Taxes, change any accounting method in respect of Taxes, settle or compromise any claim or assessment in respect of Taxes, or consent to the extension or waiver of the limitation period applicable to any claim or assessment in respect of Taxes;

(t)                        permit any insurance policy of the Company or any of its Subsidiaries to expire without being renewed or replaced by another policy of insurance on terms no less favourable; or

(u)                     agree in writing or otherwise to take any of the actions described in clause 5.1(a) through clause 5.1(t).

The parties acknowledge and hereby agree that the restrictions set forth in clause 5.1 are not intended to give the Purchaser, directly or indirectly, the right to control or direct the business or operations of the Company or its Subsidiaries at any time prior to the Closing. Prior to the Closing, the Company and its Subsidiaries shall exercise, consistent with the terms, conditions and restrictions of this Agreement, control and supervision over their own business and operations.

5.2                                 During the period from the date of this Agreement and continuing until the earlier of the termination of this Agreement or the Closing, the Purchaser shall (save with the prior written consent of the Company, such consent not to be unreasonably withheld) (a) carry on the Purchaser’s and its Subsidiaries’ business in the usual, regular and ordinary course in substantially the same manner as conducted prior to the date of this Agreement, (b) use commercially reasonable efforts to (i) pay its debts and taxes when due (except for taxes being contested in good faith by appropriate proceedings diligently pursued and for which adequate reserves have been made), and (ii) to the extent consistent with past practice and policies, preserve intact the Purchaser’s present business organisation, keep available the services of present officers and other key employees (other than as contemplated in this Agreement) and preserve relationships with customers, suppliers, distributors, licensors, licensees, and others having business dealings with it, all with the goal of preserving unimpaired the Purchaser’s and its Subsidiaries good will and ongoing businesses at the Closing.  Without limiting the generality of the foregoing, except as expressly contemplated by this Agreement, the Purchaser and its Subsidiaries shall not, without the prior written consent of the Company (such consent not to be unreasonably withheld):

(a)                                  issue, deliver, sell, allot, purchase, authorize or designate any warrants or other similar securities (including debt securities), including agreements to do the same, that are in each case convertible following the Closing into shares of common stock of Purchaser, except (1) any securities that when issued prior to the Closing will be considered outstanding common stock of Purchaser as of the last trading day prior to the Closing under the Scheme Terms and Conditions and (2) options and other equity awards made by the Purchaser as

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part of its usual annual performance review process for directors, employees and officers of the Purchaser;

(b)                                 purchase, redeem or otherwise acquire, directly or indirectly, any shares of capital stock, equity or other interests of the Purchaser or any of its Subsidiaries, or otherwise reduce its authorized or issued share capital or capitalize, repay or make any other form of distribution of any amount standing to the credit of any reserve or making any other re-organization of share capital except repurchases of Purchaser unvested shares at or below cost in connection with the termination of the employment relationship with any Purchaser employee or consultant pursuant to stock option or purchase agreements in effect on the date of this Agreement;

(c)                                  declare, set aside or pay any dividends on or make any other distributions (whether in cash, stock, equity securities or property) in respect of any capital stock or split, combine or reclassify any capital stock or issue or authorize the issuance of any other securities in respect of, in lieu of or in substitution for any capital stock of the Purchaser;

(d)                                 transfer or license to any Third Party or otherwise extend, amend or modify any rights to the Purchaser Intellectual Property, or enter into grants to transfer or license to any Third Party future rights to the Purchaser Intellectual Property, or transfer or license from any Third Party any Intellectual Property, other than (i) in the ordinary course of business consistent with past practice, (ii) pursuant to the provisions of any transfer or license entered into prior to the date of this Agreement; or (iii) such transfers or licenses which will not materially impede or delay its ability to consummate the Transactions;

(e)                                  enter into any contract outside the ordinary course of business (i) limiting the right of the Purchaser to (A) engage in any line of business that is material from the standpoint of the Purchaser’s business, operations or financial condition or (B) compete with any Third Party in any such line of business, or (ii) providing for unlimited indemnification;

(f)                                    (i) sell, lease, license, encumber or otherwise dispose of any tangible properties or tangible assets except sales of inventory in the ordinary course of business consistent with past practice, and except for the sale, lease, licensing, encumbering or disposition of property or assets not in excess of $100,000 individually or $1,000,000 in the aggregate, provided such property or assets are not material, individually or in the aggregate, to the business or prospects of the Purchaser and its Subsidiaries taken as a whole, or (ii) enter into any agreement for the purchase or sale of any interest in real property, grant any security interest in any real property, enter into any lease, sublease, license or other occupancy agreement with respect to any real property or alter, amend, modify, knowingly violate or terminate any of the material terms of any of the Purchaser’s leases;

(g)                                 make any loan, advance (other than business expense advances to Purchaser employees in the ordinary course of business consistent with past practice) or capital contribution to, or investment in, any Third Party, forgive or discharge in whole or in part any outstanding loans for borrowed money, modify any loan for borrowed money previously granted, in each case, other than in connection with the financing of ordinary course trade payables consistent with past practice;

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(h)                                 grant or pay, or enter into any agreement, arrangement or amendment to an existing agreement or arrangement providing for the granting or paying of, any severance or termination pay (whether in cash, stock, equity securities, or property) or the acceleration of vesting or other benefits to any Purchaser employee except pursuant to written agreements, policies or plans outstanding on the date hereof, or adopt any new severance or termination plan, program or arrangement, or amend or modify or alter in any manner any severance or termination plan, agreement or arrangement existing on the date hereof (including any retention, change of control or similar agreement), or grant any equity-based compensation, whether payable in cash or stock other than pursuant to any options outstanding at the date of this Agreement or as part of the usual annual performance review process for directors, employees and officers of the Purchaser;

(i)                         (i) hire any officers or employees (except for consultants and independent contractors retained for periods not greater than 6 months and without individual obligations of greater than $25,000 over such period) or enter into, or amend or extend the term of, any employment or consulting agreement with any Employee, or (ii) terminate any Employee (except for termination for cause), or take any action that would allow any Employee to claim a constructive termination or termination for “good reason”;

(j)                         materially change the amount of any insurance coverage;

(k)                      acquire any other business (including by acquiring shares or other equity interests in or the assets of any other Person) or participate in any joint venture;

(l)                         except as required by this Agreement or as otherwise deemed advisable by the Purchaser Board to comply with any law, rule, regulation or similar requirement, cause or permit any amendments to its certificate of incorporation or other charter or similar documents of the Purchaser or any of its Subsidiaries;

(m)                   permit any insurance policy of the Purchaser or any of its Subsidiaries to expire without being renewed or replaced by another policy of insurance on terms no less favourable; or

(n)                     agree in writing or otherwise to take any of the actions described in clause 5.2(a) through clause 5.2(m).

The parties acknowledge and hereby agree that the restrictions set forth in clause 5.2 are not intended to give the Company, directly or indirectly, the right to control or direct the business or operations of the Purchaser or its Subsidiaries at any time. Prior to the Closing, the Purchaser and its Subsidiaries shall exercise, consistent with the terms, conditions and restrictions of this Agreement, control and supervision over their own business and operations.

5.3                                 If the Company or any of its Subsidiaries, on the one hand, or the Purchaser and any of its Subsidiaries, on the other hand, desires to take an action that would be prohibited pursuant to clause 5.1 or clause 5.2, as applicable, then, prior to taking such action, as applicable, either the Company shall request written consent by sending an e-mail or facsimile to the following individuals at the Purchaser or the Purchaser shall request such written consent by sending an email or facsimile to the following individuals at the

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Company, and the Company or the Purchaser, as the case may be, may not take such action until such consent in writing has been received from the individuals listed below (it being understood that the Purchaser and the Company, as applicable, shall promptly evaluate and respond to any such requests and in each case such consent shall not be unreasonably withheld or delayed; provided, however, that the failure on the part of the Purchaser or the Company to promptly evaluate and respond shall under no circumstances constitute consent to such action):

Purchaser Contact Individuals:

Chief Financial Officer

SuperGen Inc

4140 Dublin Blvd, Suite 200

Dublin, CA  94568

United States

Fax:  925-551-6482

with a copy to (which copy shall not constitute proper notice):

Wilson Sonsini Goodrich & Rosati, Professional Corporation

650 Page Mill Road

Palo Alto, CA  94304

United States

Attention:  Page Mailliard

Fax:  650-493-6811

Company Contact Individuals:

Chief Executive Officer

Astex Therapeutics, Limited

Milton Road

Cambridge, CB40QA

United Kingdom

Fax:  +44(0) 1223-226201

with a copy to (which copy shall not constitute proper notice):

Wragge & Co LLP.

3 Waterhouse Square

143 Holborn

London EC1N 2SW

United Kingdom

Attention:  Kevin Jones

Fax:  +44(0) 870-904-1099

and

Cooley LLP

500 Boylston Street

Boston, MA  02116

United States

Attention:  Marc Recht

Fax:  617-937-2400

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6.                                      ACQUISITION CONDITIONS

6.1                                 Conditions to Each Party’s Obligation to Effect the Acquisition.  The obligation of each party hereto to effect the Acquisition shall be subject to the fulfilment at or prior to the time immediately before the commencement of the Scheme Court Hearing (the “Cut-Off Time”) of the following conditions:

(a)                                  Shareholder Approvals.  The Requisite Company Shareholder Approval and the Requisite Purchaser Stockholder Approval shall have been obtained.

(b)                                 No Injunctions or Restraints.  None of the parties hereto shall be subject to any order or injunction of a court of competent jurisdiction that prohibits the consummation of the transactions contemplated by this Agreement.  In the event any such order or injunction shall have been issued, each party agrees to use its commercially reasonable efforts to have any such injunction lifted.

(c)                                  No Illegality.  No statute, rule, regulation or order shall be enacted, entered, enforced or deemed applicable to the Acquisition by a Governmental Entity of competent jurisdiction that makes the Acquisition or the Scheme illegal.

(d)                                 No Government Consents.  Other than the filing of the Court Orders with the Registrar, all authorizations, consents, orders or approvals of, or declarations or filings with, or expirations of waiting periods imposed by, any Governmental Entity in connection with the Acquisition and the consummation of the Transactions, the failure of which to be filed, be obtained or occur is reasonably likely to have a Purchaser Material Adverse Effect or a Company Material Adverse Effect shall have been filed, been obtained or occurred on terms and conditions which could not reasonably be likely to have a Purchaser Material Adverse Effect or a Company Material Adverse Effect.

6.2                                 Conditions to Obligation of the Company to Effect the Acquisition.  The obligation of the Company to effect the Acquisition shall be subject to the fulfilment at or prior to the Cut-Off Time of the following conditions (any of which may be waived, in writing, by the Company in its sole discretion):

(a)                                  Representations and Warranties.

(i)                                     The representations and warranties of the Purchaser contained in Schedule 5 (other than the representations and warranties set forth in the first two sentences of Section 2.1, Section 2.2(a), the first sentence of Section 2.2(b), Section 2.4(a), Section 2.4(b) and Section 2.15 of Schedule 5) shall have been accurate as of the date of this Agreement and shall be accurate as of the Cut-Off Time as if made as of the Cut-Off Time, except to the extent that such representations and warranties refer to a specific date, in which case such representations and warranties shall have been accurate as of such date; provided, however, that this clause 6.2(a) shall be deemed to be satisfied so long as any and all inaccuracies in such representations and warranties (i) taken together as of the date of this Agreement would not be material from the standpoint of the Purchaser’s business, operations or financial condition and (ii) taken individually or together as of the Cut-Off Time would not have a Purchaser Material Adverse Effect (it being understood that, for purposes of determining the accuracy of the representations and warranties of the Purchaser for purposes of clauses (i) and (ii), all “Purchaser Material Adverse Effect” qualifications and other qualifications based on the term “in all material respects” or any similar term contained in such representations and warranties shall

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be disregarded).  The Company shall have received a certificate signed on behalf of the Purchaser by the chief executive officer and the chief financial officer of the Purchaser to such effect.

(ii)                                  The representations and warranties of the Purchaser set forth in the first two sentences of Section 2.1, Section 2.2(a), the first sentence of Section 2.2(b), Section 2.4(a), Section 2.4(b) and Section 2.15 of Schedule 5 shall have been accurate in all respects as of the date of this Agreement and shall be accurate in all respects as of the Cut-Off Time as if made as of the Cut-Off Time, except to the extent that such representations and warranties refer to a specific date, in which case such representations and warranties shall have been accurate in all respects as of such date.  The Company shall have received a certificate signed on behalf of the Purchaser by the chief executive officer and the chief financial officer of the Purchaser to such effect.

(b)                                 Agreements and Consents.  The Purchaser shall have performed or complied in all material respects with all agreements and covenants required to be performed by it under this Agreement at or prior to the Cut-Off Time; and the Company shall have received a certificate signed on behalf of the Purchaser by the chief executive officer and the chief financial officer of the Purchaser to such effect.

(c)                                  No Purchaser Material Adverse Effect.  No Purchaser Material Adverse Effect shall have occurred since the date of this Agreement and be continuing.

(d)                                 Nasdaq Listing.  Prior to the Closing Date, the Purchaser Common Stock to be issued pursuant to the transactions contemplated by this Agreement shall be approved for listing on Nasdaq subject to official notice of issuance.

6.3                                 Conditions to Obligation of the Purchaser to Effect the Acquisition.  The obligation of the Purchaser to effect the Acquisition shall be subject to the fulfilment at or prior to the Cut-Off Time of the following conditions (any of which may be waived, in writing, by the Purchaser in its sole discretion):

(a)                                  Representations and Warranties.

(i)                                     The representations and warranties of the Company contained in Schedule 5 (other than the representations and warranties set forth in the first sentence of Section 1.1, Section 1.3(a), the first two sentences of Section 1.3(b), the first sentence of Section 1.3(c), the first sentence and third sentence of Section 1.5 and Section 1.21 of Schedule 5) shall have been accurate as of the date of this Agreement and shall be accurate as of the Cut-Off Time as if made as of the Cut-Off Time, except to the extent that such representations and warranties refer to a specific date, in which case such representations and warranties shall have been accurate as of such date; provided, however, that this clause 6.3(a) shall be deemed to be satisfied so long as any and all inaccuracies in such representations and warranties (i) taken together as of the date of this Agreement would not be material from the standpoint of the Company’s business, operations or financial condition and (ii) taken individually or together as of the Cut-Off Time would not have a Company Material Adverse Effect (it being understood that, for purposes of determining the accuracy of the representations and warranties of the Company for purposes of clauses (i) and (ii), all

27

“Company Material Adverse Effect” qualifications and other qualifications based on the term “in all material respects” or any similar term contained in such representations and warranties shall be disregarded).  The Purchaser shall have received a certificate signed on behalf of the Company by the chief executive officer and the chief financial officer of the Company to such effect.

(ii)                                  The representations and warranties of the Company set forth in the first sentence of Section 1.1, Section 1.3(a), the first two sentences of Section 1.3(b), the first sentence of Section 1.3(c), the first sentence and third sentence of Section 1.5 and Section 1.21 of Schedule 5 shall have been accurate in all respects as of the date of this Agreement and shall be accurate in all respects as of the Cut-Off Time as if made as of the Cut-Off Time, except to the extent that such representations and warranties refer to a specific date, in which case such representations and warranties shall have been accurate in all respects as of such date.  The Purchaser shall have received a certificate signed on behalf of the Company by the chief executive officer and the chief financial officer of the Company to such effect.

(b)                                 Agreements and Consents.  The Company shall have performed or complied in all material respects with all agreements and covenants required to be performed by it under this Agreement at or prior to the Cut-Off Time; and the Purchaser shall have received a certificate signed on behalf of the Company by the chief executive officer and the chief financial officer of the Company to such effect.

(c)                                  No Company Material Adverse Effect.  No Company Material Adverse Effect shall have occurred since the date of this Agreement and be continuing.

(d)                                 Employees.  Each of the Employees set forth on Part 1 of a written schedule entitled “Key Employees Schedule” that was delivered by the Purchaser to the Company on the date of this Agreement and at least four (4) of the Employees set forth on Part 2 of the Key Employees Schedule shall remain as Employees of the Company as of the Cut-Off Time and shall not have taken any action to terminate, revoke or otherwise repudiate any employment arrangements he/she has with the Company.

(e)                                  Payment Schedule.  The Company shall have delivered to the Purchaser the consideration allocation schedule prepared by the Company (the “Payment Schedule”), together with a certificate of the Company signed on behalf of the Company by the chief executive officer and chief financial officer of the Company attesting to the accuracy of the Payment Schedule.

6.4                                Each of the Company and the Purchaser confirms that it is not aware of and shall not and shall procure that no member of its Group shall deliberately conceal any matter which is reasonably likely to cause any of the conditions set forth in clause 6 not to be satisfied.

7.                                      TERMINATION PAYMENTS

7.1                                 The Company shall pay the Termination Fee Amount to the Purchaser if this Agreement is terminated:

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(a)                                  by the Company pursuant to clause 9.1(d)(iv), in which case the Termination Fee Amount shall be paid at or prior to such termination by the Company, or

(b)                                 by either the Company or the Purchaser (i) pursuant to (A) clause 9.1(b)(i) provided that the Company has breached clause 4.22 prior to the time of such termination or (B) clause 9.1(b)(iv), (ii) in the case of either clause (A) or clause (B) above, within six (6) months following such termination of this Agreement, the Company enters into a definitive agreement or executes a letter of intent, memorandum of understanding, heads of terms or equivalent document with respect to an Acquisition Proposal (it being understood that in the case of clause (A), such Acquisition Proposal must be from the Third Party (or one of its affiliates) with respect to which the breach of clause 4.22 occurred) and (iii) the Company subsequently consummates the transaction contemplated by such Acquisition Proposal, in which case the Termination Fee Amount shall be paid within two Business Days following the consummation of such transaction (it being understood and agreed that for purposes of this clause, in the defined term “Acquisition Proposal” references to “15%” in such definition shall be references to “50%”); or

(c)                                  by the Purchaser pursuant to clause 9.1(c)(iii), in which case the Termination Fee Amount shall be paid within two Business Days of such termination.

7.2                                 The Purchaser shall pay the Termination Fee Amount to the Company if this Agreement is terminated:

(a)                                  by the Purchaser pursuant to clause 9.1(c)(iv), in which case the Termination Fee Amount shall be paid at or prior to such termination by the Purchaser.

(b)                                 by either the Company or the Purchaser (i) pursuant to (A) clause 9.1(b)(i) provided that the Purchaser has breached clause 4.22 prior to the time of such termination or (B) clause 9.1(b)(iii), (ii) in the case of either clause (A) or clause (B) above, within six (6) months following such termination of this Agreement, the Purchaser enters into a definitive agreement or executes a letter of intent, memorandum of understanding, heads of terms or equivalent document with respect to an Acquisition Proposal (it being understood that in the case of clause (A), such Acquisition Proposal must be from the Third Party (or one of its affiliates) with respect to which the breach of clause 4.22 occurred) and (iii) the Purchaser subsequently consummates the transaction contemplated by such Acquisition Proposal, in which case the Termination Fee Amount shall be paid within two Business Days following the consummation of such transaction (it being understood and agreed that for purposes of this clause, in the defined term “Acquisition Proposal” references to “15%” in such definition shall be references to “50%”); or

(c)                                  by the Company pursuant to clause 9.1(d)(iii), in which case the Termination Fee Amount shall be paid within two Business Days of such termination.

7.3                                 Amounts payable under clause 7.1 or clause 7.2 shall be payable to an account designated by the payee (without any set-off, deduction or withholding, save as required by law) by wire transfer of same day funds.

7.4                                 The parties acknowledge that the agreements contained in this clause 7 are an integral part of the Transactions and that, without such agreements, the parties would not enter into this Agreement.  If either party fails to promptly pay to the other party the applicable termination fee if and when it becomes due hereunder, such breaching party

29

shall pay the costs and expenses (including legal fees and expenses) in connection with any action, including the filing of any lawsuit or other legal action, taken to collect payment, together with interest on the amount of any unpaid fee at the publicly announced prime rate of Bank of America, N.A. plus five percent per annum, compounded quarterly, from the date such applicable termination fee was required to be paid.

8.                                      ACQUISITION PROPOSALS

8.1                                 As promptly as practicable (but in any event within one Business Day) after receipt of any Acquisition Proposal by the Company or its Representatives, or any material modification of or material amendment to any Acquisition Proposal or any request received by the Company or its Representatives for non-public information or inquiry which (in either case) could reasonably be expected to lead to an Acquisition Proposal, the Company shall provide the Purchaser with written notice of the material terms and conditions of such Acquisition Proposal, request or inquiry, and the identity of the Third Party making any such Acquisition Proposal, request or inquiry and a copy of all written and electronic materials provided in connection with such Acquisition Proposal, request or inquiry.  The Company shall keep the Purchaser informed in all material respects of the status and details (including all amendments or proposed amendments) of any such Acquisition Proposal, request or inquiry and shall promptly (but in any event within one Business Day after receipt) provide the other party hereto a copy of all written and electronic materials subsequently provided in connection with such Acquisition Proposal, request or inquiry.

8.2                                 Notwithstanding anything to the contrary contained in this Agreement, in the event that the Company receives an unsolicited Acquisition Proposal that the Company Board has in good faith concluded (following consultation with its outside legal counsel) is, or is reasonably likely to lead to, a Superior Offer, the Company may then take any or all of the following actions (but only (1) if the Company has not materially breached clause 4.22 in connection with such Acquisition Proposal, and (2) the Requisite Company Shareholder Approval has not yet been obtained):

(a)                                  furnish non-public information to the Third Party making such Acquisition Proposal, provided that (A) at least 48 hours prior to first furnishing any such non-public information to such party, it gives the Purchaser written notice of its intention to furnish such non-public information and the identity of the Third Party making any such Acquisition Proposal, (B) it receives from the Third Party an executed confidentiality agreement containing customary limitations on the use and disclosure of all non-public written and oral information furnished to such Third Party on the Company’s behalf, the terms of which are at least as restrictive as to confidentiality as the terms contained in the Confidentiality Agreement, provided that such agreement shall not contain terms which prevent the Company from complying with its obligations under this paragraph (which confidentiality agreement can be negotiated during the 48 hour notice period under clause (A)), and (C) contemporaneously with furnishing any such non-public information to such Third Party, it furnishes such non-public information to the Purchaser (to the extent such non-public information has not been previously so furnished or made available); and

(b)                                 engage in negotiations with the Third Party with respect to the Acquisition Proposal, provided that at least 48 hours prior to entering into negotiations with such Third Party, it gives the Purchaser written notice of the Company’s intention to enter into negotiations with such Third Party.

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The Company shall provide the Purchaser with one Business Day’s prior notice (or such lesser prior notice as is provided to the members of the Company Board) of any meeting of the Company Board at which it is reasonably expected to consider any Acquisition Proposal.

8.3           In the event that prior to the Requisite Company Shareholder Approval having been obtained, the Company Board determines that an Acquisition Proposal received without violating clause 4.22 constitutes a Superior Offer, the Company shall (a) promptly deliver notice in writing to the Purchaser of that fact (the “Company Superior Offer Notice”) which shall include the material terms and conditions of the Superior Offer and (b) at the written request of the Purchaser, negotiate in good faith with the Purchaser for a period of five (5) Business Days following the Purchaser’s receipt of the Company Superior Offer Notice (the “Revised Offering Period”).  Prior to the end of the Revised Offering Period, the Purchaser may, in its sole discretion, deliver a written revised offer to the Company that amends the terms of the Acquisition (the “Revised Offer”).  If the Purchaser submits a Revised Offer during the Revised Offering Period, the Company Board shall then hold a meeting of the Company Board to consider the Revised Offer and invite representatives of the Purchaser to present to the Company Board the Revised Offer.  Following such meeting, if the Company Board has in good faith concluded (following consultation with its outside legal counsel) that (x) the Acquisition Proposal that triggered the Revised Offering Period remains a Superior Offer when compared to the Revised Offer, and (y) taking such action is required in order for the Company Board to comply with its fiduciary duties to the shareholders of the Company under applicable Legal Requirements (the “Revised Superior Offer Determination”), the Company or the Company Board may then take any or all of the following actions following delivery of written notice to the Purchaser that the Company or the Company Board intends to take such action:

(a)           to the extent permitted pursuant to and in compliance with clause 9.1(d)(iv), enter into a binding written agreement concerning a transaction that constitutes a Superior Offer and terminate this Agreement; and

(b)           withdraw the Scheme or change the Company Board Recommendation.

8.4           Subject to the Company’s compliance with the terms of clause 8.3, (a) the Company Board may withdraw, modify or amend adversely or qualify the Company Board Recommendation (a “Change in Company Recommendation”) only if such Change in Company Recommendation is in response to an unsolicited Acquisition Proposal made to the Company which is a Superior Offer that has not been withdrawn, and (b) such Change in Company Recommendation may not be made until either (i) the Revised Offering Period lapses without the Purchaser making any Revised Offer or (ii) the Company Board has made the Revised Superior Offer Determination in accordance with clause 8.3, and the delivery of written notice to the Purchaser advising it of such fact.

8.5           As promptly as practicable (but in any event within one Business Day) after receipt of any Acquisition Proposal by the Purchaser or its Representatives, or any material modification of or material amendment to any Acquisition Proposal or any request received by the Purchaser or its Representatives for non-public information or inquiry which (in either case) could reasonably be expected to lead to an Acquisition Proposal, the Purchaser shall provide the Company with written notice of the material terms and conditions of such Acquisition Proposal, request or inquiry, and the identity of the Third Party making any such Acquisition Proposal, request or inquiry and a copy of all written and electronic materials provided in connection with such Acquisition Proposal, request or inquiry.  The Purchaser shall keep the Company informed in all material respects of

31

the status and details (including all amendments or proposed amendments) of any such Acquisition Proposal, request or inquiry and shall promptly (but in any event within one Business Day after receipt) provide the other party hereto a copy of all written and electronic materials subsequently provided in connection with such Acquisition Proposal, request or inquiry.

8.6           Notwithstanding anything to the contrary contained in this Agreement, in the event that the Purchaser receives an unsolicited Acquisition Proposal that the Purchaser Board has in good faith concluded (following consultation with its outside legal counsel) is, or is reasonably likely to lead to, a Superior Offer, the Purchaser may then take any or all of the following actions (but only (1) if the Purchaser has not materially breached clause 4.22 in connection with such Acquisition Proposal, and (2) the Requisite Purchaser Stockholder Approval has not yet been obtained:

(a)           furnish non-public information to the Third Party making such Acquisition Proposal, provided that (A) prior to first furnishing any such non-public information to such party, it gives the Company written notice of its intention to furnish such non-public information and the identity of the Third Party making any such Acquisition Proposal, (B) it receives from the Third Party an executed confidentiality agreement containing customary limitations on the use and disclosure of all non-public written and oral information furnished to such Third Party on the Purchaser’s behalf, the terms of which are at least as restrictive as to confidentiality as the terms contained in the Confidentiality Agreement, provided that such agreement shall not contain terms which prevent the Purchaser from complying with its obligations under this paragraph, and (C) contemporaneously with furnishing any such non-public information to such Third Party, it furnishes such non-public information to the Company (to the extent such non-public information has not been previously so furnished or made available);

(b)           engage in negotiations with the Third Party with respect to the Acquisition Proposal, provided that prior to entering into negotiations with such Third Party, it gives the Company written notice of the Purchaser’s intention to enter into negotiations with such Third Party; and

(c)           to the extent permitted pursuant to and in compliance with clause 9.1(c)(iv), and provided that the Purchaser Board has in good faith concluded (following consultation with its outside legal counsel) that taking such action is required in order for the Purchaser Board to comply with its fiduciary duties to the stockholders of the Purchaser under applicable Legal Requirements, enter into a binding written agreement concerning a transaction that constitutes a Superior Offer and terminate this Agreement.

The Purchaser shall provide the Company with one Business Day’s prior notice (or such lesser prior notice as is provided to the members of the Purchaser Board) of any meeting of the Purchaser Board at which it is reasonably expected to consider any Acquisition Proposal.

8.7           In the event that the Purchaser Board determines that an Acquisition Proposal received without violating clause 4.22 constitutes a Superior Offer, the Purchaser shall promptly notify the Company of that fact.

8.8           Notwithstanding anything to the contrary contained in this Agreement, (a) the Purchaser Board may withdraw, modify or amend adversely or qualify the Purchaser Board Recommendation (a “Change in Purchaser Recommendation”) only if such

32

Change in Purchaser Recommendation is in response to an unsolicited Acquisition Proposal made to the Purchaser which is a Superior Offer and which has not been withdrawn, and the Purchaser Board has in good faith concluded (following consultation with its outside legal counsel) that taking such action is required in order for the Purchaser Board to comply with its fiduciary duties to the stockholders of the Purchaser under applicable Legal Requirements, and (b) such Change in Purchaser Recommendation may not be made until the fifth Business Day following the Company’s receipt of written notice from the Purchaser advising the Company that the Purchaser Board intends to take such action and specifying the reasons therefor, including the terms and conditions of any Superior Offer that is the basis for the proposed action by the Purchaser Board.

9.             TERMINATION

9.1           This Agreement may be terminated and, subject to clause 9.2, all obligations of the parties hereunder shall cease forthwith as follows:

(a)           as agreed in writing between the Company and the Purchaser at any time prior to the Closing;

(b)           by either the Company or the Purchaser at any time prior to the Closing:

(i)            if the Closing shall not have occurred on or before the End Date for any reason; provided, however, (X) that the right of the Company to terminate this Agreement under this clause 9.1(b)(i) shall not be available if the Company’s action or failure to act have been a principal cause of or resulted in the failure of the Closing to occur on or before such date and such action or failure to act constitutes a breach of this Agreement and (Y) that the right of the Purchaser to terminate this Agreement under this clause 9.1(b)(i) shall not be available if the Purchaser’s action or failure to act have been a principal cause of or resulted in the failure of the Closing to occur on or before such date and such action or failure to act constitutes a breach of this Agreement;

(ii)           whether or not the Requisite Purchaser Stockholder Approval or the Requisite Company Shareholder Approval has been obtained, if a Governmental Entity of competent jurisdiction shall have issued an order, decree or ruling or taken any other action, in any case having the effect of permanently restraining, enjoining or otherwise prohibiting the Acquisition, which order, decree, ruling or other action is final and non-appealable;

(iii)          if the Purchaser shall have failed to obtain the Requisite Purchaser Stockholder Approval at the Purchaser Stockholder Meeting (or any postponement or adjournment thereof) at which a vote was taken on the Purchaser Resolutions; or

(iv)          if the Company shall have failed to obtain the Requisite Company Shareholder Approval at the Company Meetings at which a vote was taken on the Company Resolutions;

(c)           by the Purchaser at any time prior to the Closing:

(i)            whether or not the Requisite Purchaser Stockholder Approval has been obtained, upon a breach of any covenant or agreement on the part of

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the Company set forth in this Agreement or if any representation or warranty of the Company set forth in this Agreement (including in Schedule 5) shall be or shall have become inaccurate, in either case such that the conditions set forth in clause 6.3(a) or clause 6.3(b) would not be satisfied, provided, however, that if such breach or inaccuracy is curable by the Company through the exercise of its commercially reasonable efforts, then the Purchaser may not terminate this Agreement under this clause 9.1(c)(i) for 10 days after delivery of written notice from the Purchaser to the Company of such breach or inaccuracy, provided the Company continues to exercise commercially reasonable efforts to cure such breach or inaccuracy (it being understood that the Purchaser may not terminate this Agreement pursuant to this clause 9.1(c)(i) if such breach or inaccuracy by the Company is cured during such 10-day period); provided, however, that no cure period shall be required for a breach or inaccuracy which by its nature cannot be cured;

(ii)           whether or not the Requisite Purchaser Stockholder Approval has been obtained, if a Company Material Adverse Effect shall have occurred since the date hereof and be continuing;

(iii)          if a Company Triggering Event (as defined below) shall have occurred since the date hereof and be continuing; or

(iv)          in the event that following conditions have been satisfied:  (x) the Purchaser shall have received an unsolicited Acquisition Proposal which is a Superior Offer, (y) the Purchaser has fully complied with all provisions of clause 4.22 and clauses 8.5 through 8.8 and (z) concurrently with the termination of this Agreement pursuant to this clause 9.1(c)(iv) (and as a condition to the effectiveness of such termination), the Purchaser shall pay to the Company a fee equal to the Termination Fee Amount pursuant to clause 7.2(a);

(d)           by the Company at any time prior to the Closing:

(i)            whether or not the Requisite Company Shareholder Approval has been obtained, upon a breach of any covenant or agreement on the part of the Purchaser set forth in this Agreement, or if any representation or warranty of the Purchaser set forth in this Agreement (including in Schedule 5) shall be or shall have become inaccurate, in either case such that the conditions set forth in clause 6.2(a) or clause 6.2(b) would not be satisfied; provided, however, that if such breach or inaccuracy is curable by the Purchaser through the exercise of its commercially reasonable efforts, then the Company may not terminate this Agreement under this clause 9.1(d)(i) for 10 days after delivery of written notice from the Company to the Purchaser of such breach or inaccuracy, provided the Purchaser continues to exercise commercially reasonable efforts to cure such breach or inaccuracy (it being understood that the Company may not terminate this Agreement pursuant to this clause 9.1(d)(i) if such breach or inaccuracy by the Purchaser is cured during such 10-day period); provided, however, that no cure period shall be required for a breach or inaccuracy which by its nature cannot be cured;

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(ii)           whether or not the Requisite Company Shareholder Approval has been obtained, if a Purchaser Material Adverse Effect shall have occurred since the date hereof and be continuing;

(iii)          if a Purchaser Triggering Event shall have occurred since the date hereof and be continuing; or

(iv)          in the event that following conditions have been satisfied:  (x) the Company shall have received an unsolicited Acquisition Proposal which is a Superior Offer, (y) the Purchaser has complied with all provisions of clause 4.22 and clauses 8.1 through 8.4 and (z) concurrently with the termination of this Agreement pursuant to this clause 9.1(d)(iv) (and as a condition to the effectiveness of such termination), the Company shall pay to the Purchaser a fee equal to the Termination Fee Amount pursuant to clause 7.1(a).

For purposes of this Agreement, a “Company Triggering Event” shall be deemed to have occurred if:  (1) there is a Change in Company Recommendation; (2) if the Company Board shall have approved, endorsed, recommended or authorized the Company to enter into a definitive agreement with respect to a Superior Offer or the Company shall have entered into any letter of intent or similar document or any agreement, contract or commitment accepting any Superior Offer; or (3) the Company Board shall have passed a resolution to do any of the foregoing.  For purposes of this Agreement, a “Purchaser Triggering Event” shall be deemed to have occurred if:  (1) there is a Change in Purchaser Recommendation; (2) if the Purchaser Board shall have approved, endorsed, recommended or authorized the Purchaser to enter into a definitive agreement with respect to a Superior Offer or the Purchaser shall have entered into any letter of intent or similar document or any agreement, contract or commitment accepting any Superior Offer; or (3) the Purchaser Board shall have passed a resolution to do any of the foregoing.

9.2           Any termination of this Agreement under and in accordance with clause 9.1 will be (but will only be) effective immediately upon (or, if the termination is pursuant to clause 9.1(c)(i) or clause 9.1(d)(i) and the proviso therein is applicable, 10 days after) the delivery of written notice of the Company or the Purchaser, as applicable, to the other.  In the event of the termination of this Agreement as provided in clause 9.1, this Agreement shall be of no further force or effect and there shall be no liability to any party hereunder in connection with this Agreement or the Acquisition, except (i) as set forth in this clause 9.2 (which shall survive termination of this Agreement), (ii) as set forth in clause 7 (which shall survive termination of this Agreement).  Notwithstanding the foregoing, nothing herein shall relieve any party from liability for any intentional or wilful breach of, or any intentional misrepresentation made in, this Agreement or the other Transaction Agreements.  No termination of this Agreement shall affect the obligations of the parties contained in the Confidentiality Agreement, all of which obligations shall survive termination of this Agreement in accordance with their terms.

10.           APPROVALS AND PROCUREMENT

10.1         The parties hereto confirm to each other that they have obtained all necessary and appropriate internal authorisations for the purposes of entering into this Agreement.

10.2         Each party to this Agreement shall use all its reasonable endeavours to procure that its Representatives shall do all such acts as reasonably necessary to give effect to the terms of this Agreement, the Scheme and the Acquisition.

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11.           COSTS

Without prejudice to its other rights pursuant to this Agreement (or in relation to a breach by either party of the terms of this Agreement) each party shall pay its own costs and expenses incidental to the Acquisition.

12.           ANNOUNCEMENTS

12.1         Subject to clauses 12.2 and 12.3, prior to satisfaction or waiver (as the case may be) of the Conditions, no announcement or statement shall be made regarding the Acquisition except on a joint basis or on terms agreed in advance by the parties.

12.2         The restriction in clause 12.1 shall not apply to any announcement or statement required by applicable law, regulation, court order, the SEC or the rules of any stock exchange.

13.           MISCELLANEOUS

13.1         Notices under this Agreement shall be given in writing by personal delivery (including express overnight delivery service) or recorded delivery mail or by facsimile transmission, with a confirmation copy despatched by personal delivery or recorded delivery mail, and shall be effective when received.  Notices shall be given as follows:

(a)           if to the Purchaser:

Chief Financial Officer

SuperGen Inc

4140 Dublin Blvd, Suite 200

Dublin, CA  94568

United States

Fax: 925 551-6482

with a copy to (which copy shall not constitute proper notice):

Wilson Sonsini Goodrich & Rosati, Professional Corporation

650 Page Mill Road

Palo Alto, CA  94304

United States

Attention:  Page Mailliard

Fax:  650-493-6811

(b)           if to the Company:

Chief Executive Officer

Astex Therapeutics, Limited

Milton Road

Cambridge, CB40QA

United Kingdom

Fax:  +44(0) 1223-226201

with a copy to (which copy shall not constitute proper notice):

Wragge & Co LLP

3 Waterhouse Square

143 Holborn

London EC1N 2SW

United Kingdom

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Attention:  Kevin Jones

Fax:  +44(0) 870-904-1099

and

Cooley LLP

500 Boylston Street

Boston, MA  02116

United States

Attention:  Marc Recht

Fax:  617-937-2400

13.2         The parties acknowledge and agree that damages may not be an adequate remedy for any breach or threatened breach by it or its Representatives of this Agreement and that the party who is not in breach (the “Non-Breaching Party”) shall be entitled without proof of special damage to injunctive relief and other equitable remedy (including specific performance).

13.3         This Agreement may be executed in one or more counterparts, all of which shall be considered one and the same agreement and shall become effective when one or more counterparts have been signed by each of the parties and delivered to the other party, it being understood that no two parties need sign the same counterpart.

13.4         This Agreement, the other Transaction Agreements, and the documents and instruments and other agreements among the parties hereto referenced herein and therein (a) constitute the entire agreement among the parties with respect to the subject matter hereof and supersede all prior agreements and understandings, both written and oral, among the parties with respect to the subject matter hereof, (b) shall not be assigned by the Company by operation of law or otherwise unless otherwise specifically provided herein and (c) shall not be assigned by the Purchaser to any Third Party except that the Purchaser may assign the benefit of this Agreement to any Subsidiary of the Purchaser (which assignment shall not release the Purchaser from any of its obligations hereunder).  This Agreement may be amended by the parties hereto by action taken by or on behalf of their respective boards of directors at any time prior to the Closing; provided, however, that (x) after the Requisite Company Shareholder Approval has been obtained, no amendment may be made which by law requires further approval by the shareholders of the Company without such further approval, and (y) after the Requisite Purchaser Stockholder Approval has been obtained, no amendment may be made which by law requires further approval by the stockholders of the Purchaser without such further approval.  No modification, variation or amendment of this Agreement shall be effective unless such modification, variation or amendment is in writing and has been signed by the Company and the Purchaser.

13.5         No waiver of any breach or default under this Agreement or any of its terms shall be effective unless such waiver is in writing and has been signed by the party against which it is asserted.  Unless otherwise specifically set forth herein, no delay by any party in exercising, or failure to exercise, any right, power or remedy under this Agreement or otherwise shall constitute a waiver of the right, power or remedy, and no single or partial exercise of any right, power or remedy under this Agreement or otherwise shall prevent any further exercise of the right, power or remedy or the exercise of any other right, power or remedy.

13.6         Subject to clause 4.26, the terms of this Agreement are intended solely for the benefit of the parties hereto and are not intended to inure, and will not inure, to the benefit of any other Person.

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13.7         If any provision of this Agreement or the other Transaction Agreements or portion of this Agreement or the other Transaction Agreements is found to be wholly or partially invalid, illegal or unenforceable in any judicial proceeding, then such provision shall be deemed to be modified or restricted to the extent and in the manner necessary to render the same valid and enforceable, or shall be deemed excised from this Agreement, as the case may require, and this Agreement shall be construed and enforced to the maximum extent permitted by law, as if such provision had been originally incorporated in this Agreement as so modified or restricted, or as if such provision had not been originally incorporated in this Agreement, as the case may be.

13.8         The rights and remedies conferred on the parties in this Agreement are cumulative and in addition to all other rights and remedies available to the parties (whether hereunder or pursuant to law or equity) and the exercise by a party of one remedy will not preclude the exercise of any other remedy.

13.9         If any claim or dispute arises out of or is related to this Agreement or the other Transaction Agreements, or the interpretation, making, performance, breach or termination hereof or thereof, the parties agree that the Purchaser and the Company shall attempt in good faith to resolve such dispute within twenty (20) days of written notification of such dispute by one party to the other.  If such dispute is not so resolved within such twenty (20) day period, such claim or dispute, shall be finally adjudicated in accordance with clause 13.10.

13.10       Subject to and without limiting the fact that the approval of the Scheme by the shareholders is subject to the laws of England and Wales, this Agreement and the respective rights and obligations of the parties under this Agreement shall be governed by, and shall be determined under, the internal laws of the State of Delaware applicable to contracts between residents of the State of Delaware to be performed solely in the State of Delaware, i.e., without regard to choice of law principles.  The parties agree that (i) any action involving this Agreement shall be brought and maintained solely in the Court of Chancery of the State of Delaware, (ii) each of the parties hereto irrevocably consents to the exclusive jurisdiction and venue of the Court of Chancery in the State of Delaware, in connection with any matter based upon or arising out of this Agreement or the matters contemplated herein, agrees that process may be served upon them in any manner authorized by the laws of the State of Delaware for such persons and waives and covenants not to assert or plead any objection which they might otherwise have to such jurisdiction, venue and such process and (iii) each party agrees not to commence any legal proceedings related hereto except in such courts.

13.11       EACH OF THE PARTIES HERETO HEREBY IRREVOCABLY WAIVES ALL RIGHT TO TRIAL BY JURY AND ANY ACTION, PROCEEDING OR COUNTERCLAIM (WHETHER BASED ON CONTRACT, TORT, OR OTHERWISE) ARISING OUT OF OR RELATING TO THIS AGREEMENT OR THE ACTIONS OF ANY PARTY HERETO IN NEGOTIATION, ADMINISTRATION, PERFORMANCE OR ENFORCEMENT HEREOF.

13.12       None of the representations and warranties of the Company or the Purchaser set forth in Schedule 5 or contained in this Agreement shall survive the Closing.  Notwithstanding the foregoing, nothing herein shall relieve any party from liability for any intentional or wilful breach of, or any intentional misrepresentation made in, this Agreement or the other Transaction Agreements

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SCHEDULE 1

Agreed Form Press Announcement

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FOR IMMEDIATE RELEASE

SUPERGEN AND ASTEX THERAPEUTICS ENTER DEFINITIVE MERGER AGREEMENT

Creating a Financially Strong, International Oncology Company

DUBLIN, California and CAMBRIDGE, UK, April 6, 2011 — SuperGen, Inc. (NASDAQ: SUPG), a U.S.-based pharmaceutical company dedicated to the discovery and development of novel cancer therapies, and Astex Therapeutics Limited, a privately held, U.K.-based biotechnology company developing targeted therapies for oncology and virology, jointly announce today that they have entered into a definitive agreement to merge the two companies, subject to customary closing conditions, including regulatory and shareholder approvals.

The combined entity, to be named Astex Pharmaceuticals, Inc., is expected to create a global leader in innovative oncology drug discovery, development and commercialization with $120 million in cash and cash equivalents forecasted post deal closure.  The company plans to leverage a revenue stream from its product Dacogen®, marketed in North America by Eisai and in the rest of the world by Johnson & Johnson. The combined company’s clinical pipeline will include seven drugs in development — four of which are currently in or entering into Phase II clinical trials and three of which are currently partnered with large pharmaceutical companies.

The combined company, which is expected to be listed on NASDAQ under the symbol ASTX, expects to have:

·                  Top-tier partnerships including current partnerships with GlaxoSmithKline, Eisai, Johnson & Johnson, Novartis and AstraZeneca

·                  Nearly $2 billion in potential future milestone revenues, plus royalties

·                  An industry leading drug discovery platform to sustain future value creation

·                  Integrated operations based in two of the world’s leading biotech clusters, in the United States and the United Kingdom.

Pursuant to the terms of the agreements, SuperGen plans to purchase Astex Therapeutics Limited, paying Astex shareholders $25 million in cash, plus shares in SuperGen common stock representing 35 percent of the total post closing shares outstanding.  Subsequently, SuperGen plans to pay deferred consideration in the amount of $30 million, to be paid in stock or cash at the discretion of the combined entity, over a period of 30 months. The combined entity will assume all outstanding incentive stock options of Astex Therapeutics Limited.  Completion of the transaction will be subject to approval by

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the shareholders of each company, customary closing conditions, and U.S. and U.K. regulatory review and clearance.  The proposed transaction is expected to close in July 2011.

Under the new management structure, James S.J. Manuso, chairman, president and chief executive officer of SuperGen Inc., would become chairman and chief executive officer of Astex Pharmaceuticals, Inc., and Harren Jhoti, chief executive officer of Astex Therapeutics Limited, would become president and a member of the Board of Directors of the combined entity. The Board of Directors of the combined entity would also include Peter Fellner as vice chairman, Walter Lack, Charles Casamento, Thomas Girardi, Allan Goldberg, Tim Haines and Ismail Kola.

“We believe the combination of SuperGen and Astex accelerates SuperGen’s business model and brings together the people, partnerships, clinical assets, discovery platforms, infrastructures and capital resources to generate significant shareholder value in the years ahead,” said SuperGen’s Manuso. “The outstanding pipeline and highly regarded drug discovery platform of Astex, coupled with the product candidates, development expertise and capital resources of SuperGen, are expected to give rise to a powerful new entity capable of delivering valuable cancer therapies targeting critical medical needs.”

“We believe this merger creates a world class oncology company with a rare profile,” said Astex’s Jhoti.  “Astex Pharmaceuticals, Inc. will emerge with an industry leading drug discovery platform that we believe will continue to generate a vibrant and growing R&D pipeline, backed by an established revenue stream and a strong capital foundation.  We are very pleased about the synergies of purpose and talents that Astex and SuperGen are bringing together to create what we expect to be one of the world’s foremost oncology discovery and development companies.”

Management from SuperGen and Astex will host a conference call to discuss the proposed merger tomorrow, April 7th at 8:00 am EST / 1:00 pm BST.  A live webcast of the conference call and presentation materials are accessible on a new website http://www.astex-supergen.com, or in the investor relations section of the SuperGen or Astex Therapeutics websites at http://www.supergen.com and http://www.astex-therapeutics.com.  A webcast replay of the conference call will be available for 90 days.

On April 12th SuperGen and Astex will discuss in depth their respective pipelines and discovery operations at a joint Investor and Analyst Day in New York. Information about the live and archived webcast of these presentations will be available through the above mentioned websites.

# # #

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About SuperGen

SuperGen is a pharmaceutical company dedicated to the discovery and development of novel cancer therapeutics in epigenetic and cell signaling modulation.  SuperGen develops products through biochemical and clinical proof of concept to partner for further development and commercialization.

In addition to internal discovery programs, SuperGen has two drugs advancing in the clinic and a discovery collaboration with GlaxoSmithKline focused on epigenetic targets.

For more information about SuperGen, please visit http://www.supergen.com.

About Astex Therapeutics

Astex is a UK-based biotechnology company that discovers and develops novel small molecule therapeutics. Using its pioneering fragment-based drug discovery platform, Pyramid™, Astex has built a pipeline of molecularly-targeted oncology drugs, of which three are currently being tested in clinical trials with others in discovery and pre-clinical development.

In addition to its proprietary research programs, Astex’s productivity in lead discovery has been endorsed through numerous partnerships with major pharmaceutical companies, including AstraZeneca, GlaxoSmithKline, Johnson & Johnson and Novartis.

For further information on Astex, please visit the company’s website at www.astex-therapeutics.com.

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Note on Forward-Looking Statements

This press release contains certain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, including but not limited to, statements regarding the combined entity’s cash projections, ability to meet drug development milestones, have successful research and development capabilities, maintain strong partnerships with large pharmaceutical companies, maintain revenue streams from Dacogen, successfully integrate the development, research and financial operations of two organizations in two overseas locations, and the expected closing of the proposed Transaction.  These forward-looking statements involve certain risks and uncertainties that could cause actual results to differ materially from those indicated in such forward-looking statements, including, but not limited to, the ability of the parties to consummate the proposed Transaction, satisfaction of closing conditions precedent to the consummation of the proposed Transaction, and such other risks as identified in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2010, and the Company’s most recent Quarterly Reports on Form 10-Q, each as filed with the SEC, which contain and identify important factors that could cause the actual results to differ materially from those contained in the forward-looking statements.  The Company assumes no obligation to update any forward-looking statement contained in this press release.

Important Additional Information

SuperGen is not asking for your vote or soliciting a proxy in connection with the transaction at this time.  This press release is for informational purposes only and does not constitute an offer to sell, or the solicitation of an offer to purchase, shares of common stock of SuperGen.  This press release is not a substitute for the proxy statement that SuperGen will file with the Securities and Exchange Commission in connection with the transaction.  BEFORE MAKING ANY VOTING OR INVESTMENT DECISION WITH RESPECT TO THE TRANSACTION, INVESTORS AND STOCKHOLDERS OF SUPERGEN ARE URGED TO READ THE PROXY STATEMENT AND THE OTHER RELEVANT MATERIALS WHEN THEY BECOME AVAILABLE BECAUSE THEY WILL CONTAIN IMPORTANT INFORMATION ABOUT THE TRANSACTION. The final proxy statement will be mailed to SuperGen stockholders.  The proxy statement and other relevant materials (when they become available), and any other documents filed by SuperGen with the SEC, may be obtained free of charge at the SEC’s website at www.sec.gov; by contacting SuperGen’s Investor Relations Department by phone at (925) 560-0100 or by mail at 4140 Dublin Blvd., Suite 200, Dublin, CA 94568 USA.

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Participants in the Solicitation

SuperGen and its directors and executive officers and other persons may be deemed to be participants in the solicitation of proxies in respect of the proposed transaction.  Information regarding SuperGen’s directors and executive officers is available in SuperGen proxy statement for its 2010 annual meeting of stockholders and Annual Report on Form 10-K for the year ended December 31, 2010, which were filed with the SEC on April 30, 2010 and March 9, 2011, respectively.  Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the proxy statement and other relevant materials to be filed with the SEC when they become available.

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SCHEDULE 2

Scheme Terms and Conditions

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EXECUTION COPY

[TO FORM PART OF THE SCHEME CIRCULAR]

SCHEDULE 2

SCHEME TERMS AND CONDITIONS

Part A: Terms of the Acquisition

1.                                      Acquisition Structure

1.1                                 The Acquisition will be implemented by means of a scheme of arrangement between Astex and Scheme Shareholders under part 26 of the Act (involving a reduction of capital under Section 641 of the Act).  Full details of the Scheme will be set out in the Scheme Circular save that this sentence will not be replicated in the Terms and Conditions of this Scheme Circular.

1.2                                 If the Scheme becomes effective, it will be binding on all Scheme Shareholders irrespective of whether or not they attended or voted in favour of the resolutions at the Court Meetings or the Astex General Meeting.

2.                                      Conditions

The Scheme is conditional on satisfaction of the Conditions set out in Part B of this Appendix.

3.                                      Initial Consideration

3.1                                                 Definitions.

In this Paragraph 3:

(a)                                  “Initial Cash Amount” means the aggregate amount of cash to be paid as part of the Initial Consideration to Scheme Shareholders pursuant to the Scheme, which shall be equal to Twenty-Five Million U.S. Dollars ($25,000,000) as converted into UK Sterling at the Exchange Rate on the Business Day immediately prior to the Closing Date;

(b)                                 “Initial Share Amount” means the aggregate number of New SuperGen Shares to be issued as part of the Initial Consideration to Scheme Shareholders pursuant to the Scheme, calculated in accordance with the following formula:

X = (Y/Z) - Y,

Where X is the Initial Share Amount,

Y = the number of SuperGen Outstanding Shares, and

Z = 0.65;

(c)                                  “SuperGen Outstanding Shares” means the number of Existing SuperGen Shares issued and outstanding as of the last Trading Day immediately prior to

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the Closing Date.

3.2                                 Payment of Initial Consideration.  If the Scheme becomes effective, within one (1) Business Day after the Closing Date, SuperGen will (x) provide all necessary written instructions to its transfer agent for the issuance of the Initial Share Amount, (y) pay the Initial Cash Amount to the Paying Agent, and (z) cause the Paying Agent to distribute the Initial Share Amount and the Initial Cash Amount to the Scheme Shareholders on the register of members of Astex at the Scheme Record Time in accordance with the Payment Schedule.

Fractions of New SuperGen Shares will not be allotted or issued pursuant to the Scheme and fractional entitlements will be rounded down to the nearest whole number of New SuperGen Shares. Each Astex Shareholder who would otherwise have been entitled to receive a fractional entitlement shall receive, in lieu, an amount converted into U.K. Sterling at the Exchange Rate on the Business Day immediately prior to the Closing Date equal to such fractional entitlement at the closing price per share of one SuperGen Share on the last Trading Day immediately prior to the Closing Date.

Payment to each Scheme Shareholder eligible to receive a portion of the Initial Consideration is contingent upon the Paying Agent’s receipt of a properly completed and executed original Form W-9 for U.S. residents or Form W-8 BEN for non-U.S. residents (it being understood that the name on each such tax form must exactly match the name set forth on the Payment Schedule).  Each Scheme Shareholder eligible to receive a portion of the Initial Consideration will receive his/her/its New SuperGen Shares in book-entry form and his/her/its portion of the Initial Cash Amount in the form of a check payable to such Scheme Shareholder.

All distributions to Scheme Shareholders shall be based upon the allocations and formulae set forth in the Payment Schedule.  Provided that SuperGen causes the Paying Agent to make distributions of the Initial Consideration in conformity with the Payment Schedule, neither SuperGen nor Astex shall have any responsibility for any errors in distributions caused by either the allocations or formulae set forth in the Payment Schedule.

Any portion of the Initial Consideration that would have been paid to holders of Preferred C Shares arising from the exercise of Warrants had they been exercised prior to the Closing Date shall be withheld from the Initial Consideration and retained for distribution to holders of Warrants in the event that such Warrants are exercised after the Closing Date.  Any portion of such retained Initial Consideration associated with Warrants that expire without exercise shall be deemed forever forfeited to SuperGen.

3.3                                 Withholding Taxes.  Astex and SuperGen shall be entitled to deduct and withhold from any Initial Consideration or Deferred Consideration payable pursuant to this Part A to any Scheme Shareholder such amounts as may be required to be deducted or withheld therefrom under any provision of federal, state, local or foreign tax law or under any other applicable legal requirement.  To the extent such amounts are so deducted or withheld, such amounts shall be treated for all purposes as having been paid to the person to whom such amounts would otherwise have been paid.

3.4                                 Additional Adjustments to Aggregate Consideration.  The New SuperGen Shares payable to Scheme Shareholders under the Scheme (including as part of the Deferred Consideration) shall be adjusted to reflect appropriately the effect of any stock split, reverse stock split, stock dividend (including any dividend or distribution of securities convertible into SuperGen Shares), reorganization, recapitalization, reclassification or

47

other like change with respect to SuperGen Shares occurring or having a record date on or after the date hereof (it being understood and agreed that the foregoing adjustments to New SuperGen Shares shall include adjustments or changes of SuperGen Shares into other shares of securities of another entity as a result of a merger, consolidation, combination, share exchange or similar transaction involving SuperGen).

3.5                                 Tax Consequences.  SuperGen makes no representations or warranties to Astex or to any Scheme Shareholder regarding the tax treatment of the Scheme, or any of the tax consequences to Astex or any Scheme Shareholder of the Scheme or any of the other transactions or agreements contemplated hereby.  Astex acknowledges that Astex and the Scheme Shareholders are relying, and will continue to rely, solely on their own respective tax advisors in connection with the Scheme and the other transactions and agreements contemplated hereby.  Astex undertakes to ensure that the substance of this Paragraph 3.5 will be communicated to the Scheme Shareholders.  SuperGen shall have no responsibility for tax liabilities of Scheme Shareholders that may be incurred or arise in connection with the Scheme.

4.                                      Restrictions attaching to New SuperGen Shares that are Part of Initial Consideration and/or the Deferred Consideration

4.1                                 US Securities Law.  All New SuperGen Shares shall be issued without registration under the Securities Act in reliance on an exemption from registration provided by Section 3(a)(10) of the Securities Act and shall be freely tradable under the Securities Act, subject only to any lock-up agreements and any restrictions under Rule 144 or Rule 145 under the Securities Act that are applicable to any Scheme Shareholders who become affiliates of SuperGen following the Acquisition.

4.2                                 Execution of Lock-Up Agreements.  The Sellers’ Representative will be authorized and directed to enter into the Lock-Up Agreements on behalf of each Restricted Shareholder under power of attorney conferred by operation of the Scheme and in the event that the Sellers’ Representative is unable to (or for any reason does not) execute a Purchaser Lock-Up Agreement, then an authorized officer of the Purchaser will be authorized thereunder to enter into such Purchaser Lock-Up Agreement on behalf of each Purchaser Restricted Shareholder.

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4.3                                 Legend.  Each certificate representing New SuperGen Shares issued as part of the Initial Consideration (and any New SuperGen Shares, if any, issued as part of the Deferred Consideration during the term of the Purchaser Lock-up Agreement) to the Restricted Shareholders will be stamped with the following legend, or a legend substantially equivalent thereto:

THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO CERTAIN RESTRICTIONS ON TRANSFER AS SET FORTH IN A LOCK-UP ARRANGEMENT BINDING THE ORIGINAL HOLDER OF THESE SHARES AND ANY SUCCESSOR HOLDER, A COPY OF WHICH MAY BE OBTAINED AT THE PRINCIPAL OFFICE OF THE ISSUER.

5.                                      Rights attaching to New SuperGen Shares

5.1                                 The New SuperGen Shares issued pursuant to the Scheme, when issued, will have been duly authorised by SuperGen, and shall be validly issued, fully paid and non-assessable.

The New SuperGen Shares will be issued on identical terms to and will rank pari passu with the Existing SuperGen Shares, including the right to vote and to receive and retain all dividends and other distributions declared, paid or made on SuperGen Shares after the Closing Date. The New SuperGen Shares will not carry any right to participate in any dividends or other distributions declared or paid by SuperGen by reference to a record date prior to the Closing Date.

6.                                      Deferred Consideration

6.1                                                 Definitions.

In this Paragraph 6:

(a)                                  “Deferred Consideration Period” means the Stub Period and the 30-month period commencing on the Closing Date;

(b)                                 “Milestone Payments” means gross payments actually received by Astex, SuperGen or any other member of the Combined Group in respect of the achievement of performance milestones under Partnered Projects during the Deferred Consideration Period;

(c)                                  “Milestone Payment Statements” means statements of Milestone Payments, as prepared by SuperGen in accordance with Paragraph 6.2;

(d)                                 “Partnered Projects” means those contractual arrangements of Astex in effect as of January 1, 2011, each as set forth on Exhibit A and as such may be amended from time to time following the Closing Date, but solely with respect to the subject matter of the Milestone Payments;

(e)                                  “Payment Date” means (i) with respect to any Deferred Consideration set forth in a Milestone Payment Statement, the date falling ten (10) Business Days after the last day of the applicable Payment Period and (ii) with respect to any Dispute Consideration not set forth in a Milestone Payment Statement and that was the subject of a Dispute Notice, the date falling ten (10) Business Days after the earlier of (X) the Determination Date (as defined below in Paragraph 6.2(e)) or (Y) the date on which the Purchaser and the Sellers’ Representative otherwise agree in writing on the amount of such Deferred Consideration;

(f)                                    “Payment Period” means a period of six months, the first such period

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commencing on the Closing Date, each successive period commencing on the day after the end of the previous period and the last such period ending on the date which is the last day of the Deferred Consideration Period;

(g)                                 “Sellers’ Representative” means Abingworth Management Limited or such other Person as may be appointed as Sellers’ Representative by Scheme Shareholders from time to time in accordance with Paragraph 6.4;

(h)                                 “Share Cap” means the maximum number of New SuperGen Shares issuable, which number shall not exceed 52,500,000 SuperGen Shares (as such number of shares may be adjusted in accordance with Paragraph 3.4); and

(i)                                     “Stub Period” means the period of time commencing on 1 January 2011 and ending on (and including) the day immediately preceding the Closing Date.

6.2                                                 Deferred Consideration Procedures.

(a)                                  Delivery of Milestone Payment Statement.  Within ten (10) Business Days after the end of each Payment Period, SuperGen shall deliver to the Sellers’ Representative a Milestone Payment Statement in respect of the Milestone Payments received during the last-ended Payment Period (which, in respect of the first Payment Period, shall be deemed to include all Milestone Payments received during the Stub Period). Each Milestone Payment Statement shall set out the Partnered Projects in respect of which Milestone Payments have been paid, the amount of Milestone Payments received and the dates on which such Milestone Payments were received. In the case of the third and fifth Payment Periods, each corresponding Milestone Payment Statement shall also set forth the amount of any “true-up” payments required pursuant to Paragraph 6.3(b) or Paragraph 6.3(c), as applicable.  Where SuperGen intends to pay the Deferred Consideration otherwise than in cash (with such decision to be made in accordance with the provisions of Paragraph 6.3(f) below), the Milestone Payment Statement will also indicate whether SuperGen intends to make payments of Deferred Consideration in New SuperGen Shares or a combination of cash and New SuperGen Shares, and the proposed amount(s) of each such proposed payment in accordance with the allocations specified in Payment Schedule. If the Milestone Payment consists of a mix of both cash and New SuperGen Shares, the ratio of cash to New SuperGen Shares is intended to and shall apply pro rata to all Scheme Shareholders, subject only to rounding.

(b)                                 Confirmation Notice.  The Sellers’ Representative shall review each such Milestone Payment Statement and shall within ten (10) Business Days of receipt (the “Statement Response Period”) either (i) deliver to SuperGen a written acknowledgment confirming the Milestone Payment Statement as final (the “Confirmation Notice”) or (ii) initiate expedited dispute resolution under Paragraph 6.2(d) of this document.  If the Sellers’ Representative does not deliver a Confirmation Notice or initiate expedited dispute resolution under Paragraph 6.2(d) within the Statement Response Period, then without limiting the Purchaser’s payment obligations with respect to subsequent Payment Periods, the Deferred Consideration for the applicable Payment Period shall be an amount equal to the Milestone Payment shown in the Milestone Payment Statement and it shall be deemed final and non-appealable by any means.  In the event that some or all of the Deferred Consideration is to be paid in New SuperGen Shares, SuperGen shall pay the cash and provide the requisite instructions as to the gross number of New SuperGen Shares to be delivered to the Scheme Shareholders by the Paying Agent and, following delivery of such cash and such written instructions, the Paying Agent shall allocate the

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cash and New SuperGen Shares among the Scheme Shareholders in accordance with the Payment Schedule.  To the extent that any expedited dispute resolution under Paragraph 6.2(d) of this document relates to part only of any Milestone Payment Statement, SuperGen shall promptly (and not later than the applicable Payment Date) pay to the Paying Agent (and cause the Paying Agent to pay to the Scheme Shareholders in accordance with the terms and conditions hereof) an amount of Deferred Consideration equal to all Milestone Payments referred to in that Milestone Payment Statement that are not subject to such dispute.

(c)                                  Access.  For the purposes of reviewing the Milestone Payment Statements, SuperGen will ensure that the Sellers’ Representative and its accountants and any expert nominated and, in each case, approved by SuperGen under Paragraph 6.2(d) are given reasonable access at reasonable times to records, working papers and staff who have been engaged in the preparation of Milestone Payment Statements and that such staff answer all reasonable questions put to them.

(d)                                 Expedited Dispute Resolution.  If the Sellers’ Representative disagrees with any aspect of the Milestone Payment Statement prior to the end of the Statement Response Period, it may provide notice (a “Dispute Notice”) to SuperGen that it is referring the dispute to a firm of chartered accountants nominated jointly by the parties or (failing nomination within ten (10) Business Days after request by either party) nominated at the request of either party by the president of the Institute of Chartered Accountants in England and Wales (the “Expert”) for the purpose of resolving the dispute.  Such notice must contain a written statement of any and all matters in dispute, including a reasonably detailed description of the matters in dispute and any calculations in support of the Sellers’ Representative’s position.

(e)                                  Chartered Accountant.  The Expert so nominated shall:

(i)                                   be instructed to determine as soon as practicable the matters in dispute specified in the Dispute Notice;

(ii)                                for the purpose of making its determination, have jurisdiction to determine any matter and its terms of reference thereto;

(iii)                             adopt such procedures to assist with the conduct of the determination as it reasonably considers appropriate including instructing professional advisers to assist it in reaching its determination; and

(iv)                            act as an expert and not as an arbitrator;

and its decision will be final, binding and non-appealable on SuperGen, the Sellers’ Representative and the Scheme Shareholders except in the case of manifest error (the date of the Expert’s decision shall be referred to as the “Determination Date”). The costs of the Expert’s determination shall be borne by SuperGen; provided that if the determination of the Expert is that the Scheme Shareholders are entitled to less than 50% of the amount that is the subject of the Dispute Notice, the costs of the Expert’s determination shall be deducted from any Deferred Consideration.

6.3                                                 Payment of Deferred Consideration.

(a)                                  Payment of Deferred Consideration on Receipt of Milestone Payments.  Subject to the limitations set forth in Paragraph 6.3(d) below and the conditions

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set forth in Paragraph 6.3(e), Scheme Shareholders shall be entitled to Deferred Consideration in an amount equal to one hundred percent (100%) of the Milestone Payments (if any) actually received by Astex, SuperGen or any other member of the Combined Group in the relevant Payment Period; provided, however, that after an amount of Deferred Consideration equal to £5 million has been paid out by SuperGen (whether in cash or by the issuance of New SuperGen Shares), the amount thereafter payable with respect to each U.K. Sterling or U.S. Dollar of subsequent Milestone Payments (whether in the same or subsequent Payment Periods) shall be reduced to an amount equal to fifty percent (50%) of such Milestone Payments; and provided, further, that any funds that have been, prior to the Closing, (i) actually paid out as dividends or otherwise distributed to Astex Shareholders (in their respective capacities as such), (ii) actually expended by Astex between the execution date of the Implementation Agreement and the Closing in violation of the negative covenants set forth in clause 5.1(a) through clause 5.1(t) of the Implementation Agreement or (iii) actually expended by Astex between January 1, 2011 and the date of the execution of the Implementation Agreement if such payments would have been in violation of the negative covenants set forth in clause 5.1(a) through clause 5.1(t) of the Implementation Agreement had such expenditures occurred between the execution date of the Implementation Agreement and the Closing, shall result in a dollar-for-dollar (or Pound-for-Pound, as the case may be) reduction of the Maximum Deferred Consideration. For the purposes of this Paragraph 6.3(a) only, Milestone Payments shall be converted from U.K. Sterling into U.S. Dollars using the Exchange Rate on the last Business Day immediately prior to the date of this Agreement.

(b)                                 18-Month True Up.  Notwithstanding anything in this Agreement to the contrary, in no event shall the amount of Deferred Consideration paid by the Purchaser with respect to the third Payment Period be less than an amount equal to X minus Y, where X is equal to $15 million (less any reductions to the Maximum Deferred Consideration as described above), and Y is the aggregate amount of the Deferred Consideration paid by SuperGen with respect to the first two Payment Periods.

(c)                                  30-Month True-Up.  Notwithstanding anything in this Agreement to the contrary, in no event shall the amount of Deferred Consideration paid by the Purchaser with respect to the fifth Payment Period be less than an amount equal to X minus Y, where X is equal to $30 million (less any reductions to the Maximum Deferred Consideration as described above), and Y is the aggregate amount of the Deferred Consideration paid by SuperGen with respect to the first four Payment Periods (including any amounts actually paid pursuant to Paragraph 6.3(b) above).

(d)                                 Limitations.  Scheme Shareholders shall not be entitled to receive more than a maximum aggregate of $30 million by way of Deferred Consideration (the “Maximum Deferred Consideration”) (it being understood and agreed that each payment of Deferred Consideration shall count towards and reduce the balance of the Maximum Deferred Consideration only at the value at which such payment was calculated at the time it was made; and no subsequent increase or decrease in the value of SuperGen Shares issued in a prior Payment Period shall increase or decrease the balance of the amount of Maximum Deferred Consideration still owed by SuperGen).  By way of example and for the avoidance of doubt, in the event SuperGen owes $4,000,000 on the first Payment Period and pays the Milestone Payment for the first Payment Period in the form of $2,000,000 in cash and 1,000,000 SuperGen Shares (with the closing price per share of SuperGen common stock being $2.00 on the last Trading Day of the first Payment Period), then SuperGen will still owe

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$26,000,000 in subsequent Payment Periods regardless of whether or not the 1,000,000 SuperGen Shares issued in the first Payment Period go up or down in value over time as a result of increases or decreases in the trading price of SuperGen common stock.  Additionally, a portion of the Deferred Consideration otherwise payable to applicable Scheme Shareholders in respect of Deferred Consideration payments will be deducted on a pro rata basis from each applicable Scheme Shareholder’s share of the Deferred Consideration and paid to the Sellers’ Representative for the Sellers’ Representative Expense Reimbursement Amount in accordance with Paragraph 6.3(g).

(e)                                  Payment.  On each Payment Date following the end of each Payment Period, SuperGen shall cause the Paying Agent to distribute cash and, if applicable, a gross number of SuperGen Shares equal to the aggregate Deferred Consideration then due to the relevant Scheme Shareholders and the Sellers’ Representative in accordance with the Payment Schedule, in aggregate amounts as determined pursuant to Paragraphs 6.3(a)-(d).  Payment to each Scheme Shareholder eligible to receive a portion of the Deferred Consideration is contingent upon the Paying Agent’s receipt of a properly completed and executed original Form W-9 for U.S. residents or Form W-8 BEN for non-U.S. residents (it being understood that the name on each such tax form must exactly match the name set forth on Payment Schedule).  Each Scheme Shareholder eligible to receive a portion of the Deferred Consideration and the Sellers’ Representative will receive his/her/its New SuperGen Shares in book-entry form and his/her/its portion of the cash payment in the form of a check payable to such Scheme Shareholder.

All distributions to Scheme Shareholders and the Sellers’ Representative shall be based upon the allocations and formulae set forth in the Payment Schedule.  Provided that SuperGen causes the Paying Agent to make distributions of the Deferred Consideration in conformity with the Payment Schedule, neither SuperGen nor Astex shall have any responsibility for any errors in distributions caused by either the allocations or formulae set forth in the Payment Schedule.

Any portion of Deferred Consideration that would have been paid to holders of Preferred C Shares arising from the exercise of Warrants had they been exercised prior to the Closing Date shall be withheld from the Deferred Consideration and retained for distribution to holders of Warrants in the event that such Warrants are exercised after the Closing Date.  Any portion of such retained Deferred Consideration associated with Warrants that expire without exercise shall be deemed forever forfeited to SuperGen.

(f)                                    SuperGen Election on Form of Payment.  Deferred Consideration shall be paid by SuperGen in the form of either cash or the issuance of New SuperGen Shares (or a combination of cash and New SuperGen Shares), such allocation to be made with respect to each Payment Period in the sole and exclusive discretion, using reasonable business judgment, of the audit committee of SuperGen from time to time, with the number of New SuperGen Shares issuable with respect to a particular Payment Period computed by dividing (i) the then due but unpaid Deferred Consideration that SuperGen’s audit committee from time to time has elected to pay in the form of New SuperGen Shares by (ii) the closing price of a share of SuperGen common stock on the last Trading Day of the applicable Payment Period. The audit committee shall make its determination regarding the allocation between cash and New SuperGen Shares with respect to a particular Payment Period by no later than the last day of such Payment Period (it being understood and agreed that, if the audit committee does not make such determination prior to the last day of such Payment Period, then all Deferred Consideration payable with respect to such Payment Period shall be paid in cash).  Notwithstanding anything to the contrary herein, in no event shall SuperGen issue or be required to issue New SuperGen Shares in excess of the Share Cap (it being understood and agreed that if SuperGen has issued New SuperGen Shares equal to the Share Cap, the balance of any Deferred Consideration shall be paid in cash).  Fractions of New SuperGen Shares that would otherwise be issued as part of the Deferred

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Consideration will not be allotted or issued and fractional entitlements will be rounded down to the nearest whole number of New SuperGen Shares.  Each Astex Shareholder who would otherwise have been entitled to receive a fractional entitlement shall receive, in lieu, an amount converted into U.K. Sterling at the Exchange Rate on the Business Day immediately prior to the date of this Agreement equal to such fractional entitlement at the closing price per share of one share of SuperGen common stock on the last Trading Day immediately prior to the applicable Payment Date.

(g)                                 Sellers’ Representative Expense Reimbursement Amount.  In accordance with the Payment Schedule, SuperGen shall cause the Paying Agent to pay out of the first amounts of Deferred Consideration otherwise payable to Scheme Shareholders an amount in cash equal to One Hundred Thousand U.S. Dollars ($100,000) (the “Sellers’ Representative Expense Reimbursement Amount”) to the Sellers’ Representative to be held by the Sellers’ Representative in trust for the benefit of the Scheme Shareholders, to be used by the Sellers’ Representative solely for the payment of out-of-pocket expenses incurred by the Sellers’ Representative in connection with the performance of the Sellers’ Representative’s duties and obligations hereunder.  The Sellers’ Representative Expense Reimbursement Amount shall be deducted on a pro rata basis from each applicable Scheme Shareholder’s portion of the Deferred Consideration otherwise payable.  No later than ten (10) Business Days following the last Payment Date in Paragraph 6, the Seller’s Representative shall distribute the balance of any funds held by it in respect of the Sellers’ Representative Expense Reimbursement Amount to the applicable Scheme Shareholders on a pro rata basis consistent with the original deductions of such amounts from the applicable Scheme Shareholders.

6.4                                                 Sellers’ Representative

(a)                                  The first Sellers’ Representative shall be Abingworth Management Limited.

(b)                                 The Scheme Shareholders will each indemnify and hold Abingworth Management Limited and its directors, officers, agents and employees (“Abingworth”) harmless against any losses, claims, damages or liabilities to any person arising out of or in connection with Abingworth’s role as Sellers’ Representative (including without limitation any legal or accounting fees and expenses), except to the extent that any such loss, claim, damage or liability results from Abingworth’s gross negligence or bad faith.

(c)                                  The Scheme Shareholders shall be entitled to replace Abingworth or any other Person being Sellers’ Representative from time to time and appoint another Person in their place upon not less than 10 calendar days’ written notice to the Sellers’ Representative and to SuperGen, signed by Scheme Shareholders who held 75% or more of the Scheme Shares at the Closing Date.  Any Person appointed as replacement Sellers’ Representative shall as a condition to appointment have confirmed in writing to SuperGen that he, she or it has agreed to act in that capacity and that he, she or it is not entitled to any compensation from SuperGen.

(d)                                 The provisions of Paragraph 6.4(b) shall apply equally to any Person appointed as replacement Sellers’ Representative.

6.5                                 Any notice or communication given or received by, and any decision, action, failure to act, agreement, consent, settlement, resolution or instruction of, the Sellers’ Representative shall constitute a notice or communication to or by, or a decision, action, failure to act, agreement, consent, settlement, resolution or instruction of all Scheme Shareholders and shall be final, binding and conclusive upon each such Scheme Shareholder and SuperGen shall be entitled to rely upon all such actions or inactions of the Sellers’ Representative as the actions or inactions of the Scheme Shareholders.

7.                                      Allocation of Consideration

7.1                                                 Solely for the purpose of the Company’s determination of the operation of the Articles in relation to the Acquisition (which is deemed by the Company to be a “Sale” for the purposes of the Articles), and specifically for the Company’s determination of the allocations of Consideration to Scheme Shareholders pursuant to the Scheme, any part of the Consideration payable in:

(a)                                  cash shall be deemed to have been converted from U.S. Dollars into U.K. Sterling using the 30-day moving average Exchange Rate for the period immediately prior to the date of the Implementation Agreement; and

(b)                                 New SuperGen Shares shall be deemed to have been valued based on the 30-day moving average stock price for Existing SuperGen Shares for the period

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immediately prior to the date of the Implementation Agreement, such value then being converted into U.K. Sterling in accordance with Paragraph 7.1(a)(i),

in each such case, as determined by the Company in its absolute discretion.  Notwithstanding the foregoing, for the purposes of Article 2(b)(ii) of the Articles, the Company’s allocation of Consideration shall be applied to satisfy the entitlements under subparagraphs (A) through (D) in order of priority and no Scheme Shareholder shall be entitled to any part of the Consideration unless and until each of the entitlements having priority under that Article has been satisfied in full.  If any instalment of Consideration comprises cash and New SuperGen Shares, such cash and shares shall be allocated by the Company to Scheme Shareholders in the same proportions that the two elements bear to one another when paid (as cash) or instructed for issuance (as shares) to the Paying Agent by SuperGen, and, for the avoidance of doubt, shall not be applied in any way which requires either to be applied first before the application of the other in satisfaction of the entitlements of Scheme Shareholders to the Consideration under the Articles.

7.2                                                 The Consideration shall be allocated among Scheme Shareholders in accordance with their entitlements under the Articles as modified by this Paragraph 7, and it shall be the sole responsibility of the Sellers’ Representative to ensure that the Payment Schedule reflects the allocation principles set out in this Paragraph 7  as well as the pro rata deduction for the Sellers’ Representative Expense Reimbursement Amount.

7.3                                                 For the avoidance of doubt, nothing in this Paragraph 7 shall have the effect of increasing or decreasing any amounts payable or issuable by SuperGen pursuant to Paragraphs 3.2 and 6.3 (which specify the maximum amount of consideration payable by SuperGen). SuperGen shall have no liability or responsibility whatsoever for the allocation of the Consideration to Scheme Shareholders provided it has fulfilled its obligations pursuant to Paragraphs 3.2 and 6.3 and no Scheme Shareholder shall have any claim against SuperGen on any basis whatsoever arising as a result of the application of this Paragraph 7.

7.4                                                 In circumstances where Paragraph 3.4 applies as a result of replacement shares or securities being issued as a consequence of any merger, consolidation, combination, share exchange or similar transaction involving SuperGen, then the Sellers’ Representative shall have sole discretion as to how such replacement shares or securities are valued  for the purposes of determining the operation of the Articles in relation to the Acquisition and specifically in determining the allocations of Consideration to Scheme Shareholders pursuant to the Scheme.

8.                                      Post-Signing Permitted Bonuses

Following the Closing Date, SuperGen shall cause the Company to pay the SIP Participants the Permitted Bonuses no later than two Business Days prior to the date on which SIP Participants are obliged to remit any tax payments arising from the cancellation of the Ordinary Shares currently held subject to the terms of the SIP.

Part B: Conditions of the Acquisition

The Acquisition is conditional upon the Scheme becoming unconditional and becoming effective by not later than August 31, 2011, or such later date (if any) as Astex and SuperGen may agree and (if required) the Court may allow.

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1.                                      Conditions to the Scheme:

1.1                                 The Scheme is conditional upon:

(a)                                  the approval of the Scheme by a majority in number of each class of Scheme Shareholders, who are on the register of members of Astex at the Voting Record Time, present and voting either in person or by proxy, at the Court Meetings (or at any adjournment of such meetings) representing seventy-five percent (75%) or more in value of the Scheme Shares of that class voted by those Scheme Shareholders;

(b)                                 the resolution(s) required to implement the Scheme and set out in the notice of the Astex General Meeting being duly passed by the requisite majority at the Astex General Meeting (or at any adjournment of such meeting); and

(c)                                  the sanction (with or without modification, any such modification being on terms reasonably acceptable to Astex and SuperGen) of the Scheme and the confirmation of the Reduction of Capital by the Court being obtained and office copies of the Court Orders being delivered to the Registrar of Companies.

1.2                                 In addition, the Acquisition is conditional upon the following matters, and accordingly the necessary actions to make the Scheme effective will not be taken unless such Conditions have been satisfied (where capable of satisfaction), or waived, prior to the Scheme being sanctioned by the Court in accordance with Paragraph 1 above:

(a)                                  the passing at the SuperGen Special Stockholders Meeting (or any adjournment thereof) of the SuperGen Proposal; and

(b)                                 the Implementation Agreement not having terminated or having been terminated in accordance with its terms prior to the Scheme Court Hearing; and

(c)                                  the conditions in Section 6 of the Implementation Agreement having been satisfied or waived by the applicable party prior to the Scheme Court Hearing.

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DEFINED TERMS

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EXHIBIT A

ASTEX PARTNERED PROJECTS

1.     AstraZeneca AB — Research Collaboration & License Agreement (BACE) (21 February 2003) & Amendments

2.     Institute of Cancer Research, Cancer Research Technology Limited, The Wellcome Trust Limited — Research Collaboration & Intellectual Property Management Agreement (BRAF) (16 February 2004) & Amendments

3.     AstraZeneca — Collaboration & License Agreement (PKB) (8 July 2005) & Amendments

4.     Novartis International Pharmaceutical Ltd — Collaboration & Licence Agreement (CDK) (2 December 2005) & Amendments

5.     Janssen Pharmaceutical NV — Collaboration & Licence Agreement (FGFR & other targets) (6 June 2008) & Amendments

6.     The Wellcome Trust Limited — Deed of Subscription, Deed of Adherence & Collaboration Agreement (Seeding Drug Discovery - HCV protease inhibitors) (4 February 2009) & Amendments

7.     Multiple Myeloma Research Foundation — Research Agreement (AT7519 Phase II) (24 February 2009)

8.     GlaxoSmithKline LLC & Glaxo Group Limited — Research & Development Collaboration & License Agreement (Multiple targets) (12 November 2009)

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SCHEDULE 3

Transaction Timetable

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SCHEDULE 4

Part 1

Company Irrevocable Voting Undertakings

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ASTEX THERAPEUTICS LIMITED

IRREVOCABLE UNDERTAKING

Index

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IRREVOCABLE UNDERTAKING

To:          SuperGen, Inc

4140 Dublin Blvd

Suite 200

Dublin

CA 94568

USA

and:        Astex Therapeutics Limited

2011

Dear Sirs

Acquisition by SuperGen, Inc. (“SuperGen”) of Astex Therapeutics Limited (“Astex” or the “Company”)

1.             Undertakings

1.1           In consideration of SuperGen agreeing to acquire the entire issued and to be issued share capital of the Company (the “Acquisition”) by way of a scheme of arrangement under section 895 of the Companies Act 2006 (the “Scheme”), on the terms and subject to the conditions of a scheme circular (the “Scheme Circular”) to be produced in connection with the Acquisition containing terms and conditions set out at Appendix 2 of the Implementation Agreement dated as of                                    2011 between SuperGen and the Company (the “Implementation Agreement”, with capitalized terms not otherwise defined herein having the meanings given to such terms in the Implementation Agreement), I, the undersigned, hereby irrevocably and unconditionally (save as specified below) undertake, represent and warrant to and confirm and agree with SuperGen, with effect from the date of this undertaking, that:

(a)                                  I am the beneficial owner (and unless otherwise specified in the schedule to this undertaking am also the registered holder and to the extent that I am not the registered holder I will (so far as I am able) procure compliance by such registered holder(s) with the terms of this undertaking), of the number of shares in the capital of the Company (the “Shares”) specified in paragraph 1 of the schedule to this undertaking (the “Committed Shares”) (which expression shall include any other Shares acquired or purchased by the undersigned after the date of this undertaking or any other shares or interests attributable to or derived from such Committed Shares);

(b)                                 I shall exercise, or (so far as I am able in relation to shares of which I am the beneficial owner but not the registered owner (“Beneficial Owned Shares”)) procure the exercise of, all voting rights attaching to the Committed Shares to vote in favour of all resolutions to approve the Scheme, and any related matters proposed at any general or class meeting (the “General Meeting”) and the Court convened meetings (the “Court Meetings”) of the Company to be convened and held in connection with the Scheme, or at any adjournment of any such meeting;

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(c)                                  I shall execute, or (so far as I am able in relation to Beneficial Owned Shares) procure the execution of, any forms of proxy in respect of the Committed Shares required by SuperGen appointing any person nominated by SuperGen to attend and vote at any General Meeting or Court Meeting in respect of the resolutions to approve the Scheme, and any related matters, and shall ensure that any such executed forms of proxy are received by Astex not later than 3.00 p.m. on the fifth business day (being any day which is not a Saturday, Sunday, a bank holiday or a public holiday in England and Wales (a “Business Day”)) after receipt by me of the formal document setting out the terms and conditions of the Scheme (the “Scheme Document”);

(d)                                 I shall not revoke, or procure the revocation of, the terms of any proxy submitted in accordance with sub-paragraph 1.1(c), other than by attendance at any General Meeting or Court Meeting where I vote in favour of the Scheme in accordance with this undertaking;

(e)                                  I have been granted share options under the share schemes (the “Share Schemes”) over the number of shares as specified in paragraph 2 of the schedule to this undertaking (the “Options”) and confirm that the Options are still subsisting as of the date of this undertaking and that I am beneficially entitled to the Options and, in respect of those Options, I undertake that following the making of the proposals to the holders of options under the Share Schemes as are set out in the Implementation Agreement, in respect of such of the Options which become exercisable in accordance with the rules of the Share Schemes as a result of the Acquisition, I shall either:

(i)            accept such proposals made in respect of such Options; or

(ii)           exercise in full the relevant Option; and

(iii)          vote in favour of all resolutions to approve the Scheme in accordance with paragraph 1.1(c) above in respect of all of the Shares that I receive where the exercise price per Share of such Option is less than the offer price per Share under the terms of the Acquisition.

1.2           In the event I do acquire or purchase any Shares after the execution of this undertaking, such Shares shall be deemed to be included in the definition of “Committed Shares”.

2.             Non-dealing / covenants

Unless and until the Scheme lapses or is withdrawn, or the Implementation Agreement is otherwise terminated, I will not and I will (so far as I am able in relation to Beneficial Owned Shares) procure that any registered holder of the Committed Shares will not, directly or indirectly:

(a)                                  except pursuant to the Acquisition, sell, transfer, charge, encumber, grant any options over or otherwise dispose of, or permit the sale, transfer, charging, encumbering or granting of any option over or other disposal of, all or any of the Committed Shares or of any interest therein; provided, however, that this clause (a) shall not prohibit a sale or transfer of Committed Shares by the undersigned (a) to any member of the undersigned’s immediate family, or to a trust for the benefit of the undersigned or any member of the undersigned’s immediate family, or (b) upon the death of the undersigned; provided, however, that a sale or transfer referred to in this sentence shall be permitted only if, as a precondition to such sale or transfer, the transferee agrees in writing, satisfactory in form and substance to SuperGen, to be bound by all of the terms of this undertaking; nor

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(b)                                 without limiting the proviso to clause (a) above, accept, encourage or agree to accept any other offer (whether made or yet to be made at the date of such agreement) in respect of all or any of the Committed Shares or any other shares in the capital of the Company whether conditional or unconditional (by whatever means the same is to be implemented); nor

(c)                                  vote in favour of any of the following to the extent that Astex is prohibited from taking any such action by the Implementation Agreement:

(i)                                     any resolution to approve any scheme of arrangement in relation to Astex which is proposed in competition with the Acquisition;

(ii)                                  any sale, lease, sublease, license, sublicense or transfer of a material portion of the rights or other assets of Astex;

(iii)                               any reorganization, recapitalization, dissolution or liquidation of Astex;

(iv)                              save as may be required in connection with the Scheme any amendment to the Astex articles of association;

(v)                                 save as may be required in connection with the Scheme any material change in the capitalization of Astex or in Astex’s corporate structure; or

(vi)                              any other action which is intended, or would reasonably be expected to impede, interfere with, materially delay or adversely affect the Acquisition or any of the other transactions contemplated by the Implementation Agreement; nor

(d)                                 without the written consent of SuperGen, purchase or otherwise acquire (other than by exercise of existing Options) directly or indirectly any shares or other securities in the Company or any interest therein; nor

(e)                                  convene any meeting of the members of the Company in any capacity as a shareholder, nor exercise or permit the exercise of the voting rights attaching to the Committed Shares in any manner which I know would be likely to frustrate the Acquisition or prevent the Scheme becoming effective; nor

(f)                                    (other than pursuant to the Acquisition) enter into any agreement, arrangement or obligation or permit any agreement, arrangement or obligation to be entered into in relation to the Committed Shares with any person whether conditional or unconditional to do all or any of the acts referred to in this paragraph 2; nor

(g)                                 During the pre-closing period, take any action that the Company is prohibited from taking pursuant to section 4.23 of the Implementation Agreement;

provided, however, that notwithstanding anything to the contrary contained in this undertaking, nothing in this undertaking limits or affects, or gives rise to any liability or obligation of the undersigned by virtue of, any actions taken by the undersigned in his or her capacity as an officer or director of the Company, as applicable, in proper discharge of my fiduciary duties as a director of the Company or in respect of obligations that would otherwise be imposed by this undertaking that are inconsistent with the proper discharge of my fiduciary duties as a director of the Company, in each case including any actions taken in connection with the exercise of the rights of the Company or its board of directors (or any committee thereof) under the Implementation Agreement.

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3.             Confirmations

I hereby irrevocably and unconditionally undertake, represent and warrant to and confirm and agree with SuperGen that:

(a)                                  the details of all my interests in the Company and SuperGen at the date hereof contained in the schedule to this undertaking are true and accurate and that my interests are correctly described and the registered holder(s) of the Shares to which they relate as set out in the schedule are true and accurate in all respects;

(b)                                 the execution and delivery of this undertaking by me will not and the performance by me of the obligations under this undertaking will not: (i) conflict with or violate any legal requirement or order applicable to me or by which I or any of my properties are or may be bound or affected; (ii) result in or constitute (with or without notice or lapse of time) any breach of or default under, or give to any other person (with or without notice or lapse of time) any right of termination, amendment, acceleration or cancellation of, any contract to which I am a party or by which I or any of my properties is or may be bound or affected, other than any such breach, default, termination, amendment, acceleration or cancellation that would not, individually or in the aggregate, have an adverse effect on my ability to comply with the terms of or to fulfill my obligations under, this undertaking; or (iii) result (with or without notice or lapse of time) in the creation of any encumbrance on any of the Committed Shares pursuant to any contract to which I am is a party or by which I or any of my properties is or may be bound or affected;

(c)                                  I will within one Business Day notify SuperGen in writing if for any reason the details contained in the schedule to this undertaking cease to be true and complete;

(d)                                 I have full individual, corporate or other entity power and authority to enter into this undertaking and to perform all my obligations hereunder in accordance with their terms and this undertaking has been duly executed and delivery by me and constitutes my legal, valid and binding obligations, subject to: (a) laws of general application relating to bankruptcy, insolvency and the relief of debtors; and (b) rules of law governing specific performance, injunctive relief and other equitable remedies.

4.             Director’s undertaking

4.1           Subject to paragraph 4.2 below (and save where (i) I am required not to do so by virtue of my fiduciary duties as a director (having regard to written legal advice) or (ii) the Implementation Agreement terminates or is terminated), as a director of the Company, I further hereby irrevocably and unconditionally (save as specified below) undertake, represent and warrant to SuperGen and agree with SuperGen that:

(a)                                  I will recommend to all the shareholders of the Company that: they should vote in favour of all resolutions to approve the Scheme;

(b)                                 I will join in the making of a recommendation to be contained in the Scheme Circular recommending them to vote in favour of all resolutions to approve the Scheme;

(c)                                  so far as it is within my power, I will, upon the Scheme becoming effective in all respects and so far as is not inconsistent with English law, join the other members of the board of the Company in appointing any persons nominated by SuperGen to the board of the Company and its subsidiaries and transfer to or

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procure the transfer to and procure the registration of SuperGen or its nominee(s) as the holder of any shares in the subsidiaries of the Company of which I am or any nominee of the Company or another subsidiary of the Company is the holder;

(d)                                 upon the Scheme becoming effective and so far as is not inconsistent with English law, I will procure, so far as I am reasonably able, and at the expense of SuperGen, the registration of  SuperGen or its nominee(s) as the holder(s) of the Committed Shares and all other shares the subject of the Scheme;

4.2           Each of the undertakings set out in this paragraph 4 shall be subject always to any relevant law or regulation and my fiduciary duties and statutory duties and obligations as a director of the Company and nothing that I may do by reason of my fiduciary duties and statutory duties and obligations to the Company or pursuant to any relevant law or regulation shall constitute a breach of this paragraph 4.

4.3           So far as I am aware the proposed conditions of the Scheme can currently be satisfied and I am not aware of any circumstances that currently exist whereby such conditions would become incapable of being satisfied before the Scheme becomes effective and I undertake to notify SuperGen promptly if I become aware of any such circumstances during such time provided that I accept no legal liability to SuperGen if any such condition is not satisfied.

4.4           If requested by SuperGen I further undertake to deliver a letter to the Company on closing of the Acquisition or at such other time as requested in writing by SuperGen following closing of the Acquisition pursuant to which I shall:

(a)                                  resign as a director of the Company with effect from the close of the meeting of the directors of the Company at which the letter is presented;

(b)                                 confirm and agree that I have no claim or right of action of any kind outstanding against the Company (whether arising in contract, in tort, by statute or otherwise) in respect of compensation for loss of office; and

(c)                                  to the extent that any such claim exists or may exist, irrevocably waive such claim and release the Company, its officers and employees from any liability in respect thereof.

5.             Duration

The undertakings set out herein and the appointment set out in paragraph 7 below shall terminate on the earliest of (a) the closing of the Acquisition, (b) the date (if any) on which the Scheme lapses or is withdrawn and (c) the date (if any) on which the Implementation Agreement terminates or is terminated, and upon and following any such termination, this undertaking shall be deemed void and have no further force or effect save in relation to those rights which shall have accrued following any breaches of the undertakings set out herein which occurred prior to such date.

6.             General

6.1           In this undertaking, references to the “Scheme” mean any scheme of arrangement in relation to Astex under section 895 of the Companies Act 2006 (including any new, renewed or revised scheme of arrangement) for the acquisition by SuperGen of all the issued share capital of Astex other than that already owned by SuperGen provided that the terms of such Scheme are in the good faith opinion of the Company no less favourable overall including from a financial point of view to the holders of Shares  than the terms and conditions of the Scheme as set out in the Implementation Agreement. References to the Scheme lapsing or being withdrawn shall, for the avoidance of

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doubt, include, without limitation, circumstances where the resolutions required to implement the Scheme are not passed at the relevant Court Meetings and General Meetings (or at any adjournments thereof), such meetings are adjourned indefinitely and/or the Court does not sanction the Scheme (or any associated reduction of capital).

6.2           I understand that the information provided to me in relation to the Scheme is given in confidence and must be kept confidential and not disclosed to any third party (other than a professional adviser) until the Press Announcement is released or the information has otherwise become generally available, save that disclosure may be made (i)  to  the extent required by law or any other legal or regulatory requirement or (ii) where the relevant information was in my knowledge or possession prior it being disclosed to me by either Astex or SuperGen in connection with the Scheme or (iii) was developed independently and without reference to the confidential information of Astex or SuperGen as evidenced with contemporaneous written records or (iv) was public knowledge  or has become public knowledge other than through fault on my part or (v) was properly provided to me by an independent third party who has no obligation of secrecy to Astex or SuperGen.

6.3           I recognise and acknowledge that if I should fail to comply with my obligations and undertakings hereunder, money damages may not be an adequate remedy and I further agree that, in the event of any breach or threatened breach by me of any covenant or obligation contained in this undertaking, SuperGen shall be entitled (in addition to any other remedy that may be available to it) to seek to obtain: (a) a decree or order of specific performance to enforce the observance and performance of such covenant or obligation; and (b) an injunction restraining such breach or threatened breach.  I further agrees that neither SuperGen nor any other person shall be required to obtain, furnish or post any bond or similar instrument in connection with or as a condition to obtaining any remedy referred to in this paragraph 6.3, and I irrevocably waive any right I may have to require the obtaining, furnishing or posting of any such bond or similar instrument.

6.4           Any time, date or period mentioned in this undertaking may be extended by mutual agreement between SuperGen and me or otherwise as provided herein but as regards any time, date or period originally fixed or extended as aforesaid time shall be of the essence.

6.5           With regard to any of the Committed Shares which are not registered in my name, the undertakings, agreements and obligations of whatsoever nature contained in this undertaken are given by me subject to the conditions set out in paragraph 5 above but otherwise on behalf of the registered holder(s) of such Committed Shares and I undertake (so far as I am able in relation to Beneficial Owned Shares) to procure the compliance by the registered holder(s) of such Committed Shares with the undertakings, agreements and obligations of whatsoever nature contained in this undertaking.

6.6           If any provision or part of any provision of this undertaking, or the application of any such provision or part thereof to any person or set of circumstances, shall be determined to be invalid or unenforceable in any jurisdiction to any extent, then: (a) such provision or part thereof shall, with respect to such circumstances and in such jurisdiction, be deemed amended to conform to applicable legal requirements so as to be valid and enforceable to the fullest possible extent; (b) the invalidity or unenforceability of such provision or part thereof under such circumstances or in such jurisdiction shall not affect the validity or enforceability of such provision or part thereof under any other circumstances or in any other jurisdiction; and (c) the invalidity or unenforceability of such provision or part thereof shall not affect the validity or enforceability of the remainder of such provision or the validity or enforceability of any other provision of this undertaking.  Each provision of this undertaking is separable

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from every other provision of this undertaking, and each part of each provision of this undertaking is separable from every other part of such provision.

6.7           This undertaking, the Implementation Agreement and any other documents delivered by the parties in connection herewith and therewith constitute the entire agreement between the parties with respect to the subject matter hereof and thereof and supersede all prior agreements and understandings between the parties with respect thereto.

6.8           This undertaking may not be amended, modified, altered or supplemented other than by means of a written instrument duly executed and delivered on behalf of SuperGen and me.

6.9           Except as provided herein, neither this undertaking nor any of the interests or obligations hereunder may be assigned or delegated by me, and any attempted or purported assignment or delegation of any of such interests or obligations shall be null and void.  Subject to the preceding sentence, this undertaking shall be binding upon me and my heirs, estate, executors and personal representatives and my successors and assigns, and shall inure to the benefit of SuperGen and its successors and assigns.  Without limiting any of the restrictions set forth in this undertaking, this undertaking shall be binding upon any person to whom any Committed Shares are transferred.  Nothing in this undertaking is intended to confer on any person (other than SuperGen and its successors and assigns) any rights or remedies of any nature.

6.10         The rights and remedies of SuperGen under this undertaking are not exclusive of or limited by any other rights or remedies which it may have, whether at law, in equity, by contract or otherwise, all of which shall be cumulative (and not alternative).

6.11         This undertaking may be executed in separate counterparts, each of which shall constitute an original and all of which, when taken together, shall constitute one agreement.  The exchange of a fully executed undertaking (in counterparts or otherwise) by electronic transmission in .PDF format or by facsimile shall be sufficient to bind the parties to the terms and conditions of this undertaking.

6.12         No failure on the part of SuperGen to exercise any power, right, privilege or remedy under this undertaking, and no delay on the part of SuperGen in exercising any power, right, privilege or remedy under this undertaking, shall operate as a waiver of such power, right, privilege or remedy; and no single or partial exercise of any such power, right, privilege or remedy shall preclude any other or further exercise thereof or of any other power, right, privilege or remedy.  SuperGen shall not be deemed to have waived any claim available to SuperGen arising out of this undertaking, or any power, right, privilege or remedy of SuperGen under this undertaking, unless the waiver of such claim, power, right, privilege or remedy is expressly set forth in a written instrument duly executed and delivered on behalf of SuperGen; and any such waiver shall not be applicable or have any effect except in the specific instance in which it is given.

7.             Power of attorney

Subject to paragraph 5 above, I hereby irrevocably and by way of security for my obligations hereunder appoint, severally, SuperGen and any director of SuperGen as my attorney to execute and deliver all  documents and do all such other acts and things as may be necessary for, or incidental to, the voting of the Committed Shares and/or the performance of my obligations under this undertaking on my behalf in the event of my failure to comply with any provision of this undertaking within the specified period and I irrevocably undertake to ratify such act if called upon to do so.

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8.             Notices

8.1           Any notice, demand or other communication given or made under or in connection with the matters contemplated by this undertaking shall be in writing and shall be delivered personally or sent by fax or prepaid first class post (air mail if posted to or from a place outside the United Kingdom):

In the case of me to:

and shall be deemed to have been duly given or made as follows:

(a)           if personally delivered, upon delivery at the address of the relevant party;

(b)           if sent by first class post, within the United Kingdom, two Business Days after the date of posting;

(c)           if sent by air mail, three Business Days after the date of posting; and

(d)           if sent by fax, when despatched,

provided that if, in accordance with the above provisions, any such notice, demand or other communication would otherwise be deemed to be given or made after 5.00 p.m. on a Business Day such notice, demand or other communication shall be deemed to be given or made at 9.00 a.m. on the next Business Day.

8.2           A party may notify the other party to this undertaking of a change to its name, relevant addressee, address or fax number for the purposes of paragraph 8.1 provided that such notification shall only be effective on:

(a)           the date specified in the notification as the date on which the change is to take place; or

(b)           if no date is specified or the date specified is less than five Business Days after the date on which notice is given, the date falling five Business Days after notice of any such change has been given.

9.             Governing law and submission to jurisdiction

9.1           This undertaking and any dispute, claim or obligation (whether contractual or non-contractual) arising out of or in connection with it, its subject matter or formation shall be governed by English law.

9.2           The parties irrevocably agree that the English courts shall have exclusive jurisdiction to settle any dispute or claim (whether contractual or non-contractual) arising out of or in connection with this undertaking, its subject matter or formation.

IN WITNESS this undertaking has been executed as a deed and delivered on the date appearing at the head of page 1.

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THE SCHEDULE

Interests in relevant securities of the Company

1.             Shares

The relevant securities of Company in which I have an interest are as follows:

Interests in shares

2.             Options

The relevant securities of Company in which I have an interest (or a right to subscribe) are as follows:

Interests in options