Exhibit 99.1

THIS DOCUMENT IS IMPORTANT AND REQUIRES YOUR IMMEDIATE ATTENTION.

THIS DOCUMENT INCLUDES A PROPOSAL WHICH, IF IMPLEMENTED, WILL RESULT IN THE DELISTING OF THE AMERICAN DEPOSITARY SHARES, EACH REPRESENTING FIVE ORDINARY SHARES IN SUMMIT THERAPEUTICS PLC (INCORPORATED IN ENGLAND AND WALES) (THE “OLD SUMMIT ADSs”) FROM THE NASDAQ GLOBAL MARKET AND THE LISTING OF THE SHARES OF COMMON STOCK OF SUMMIT THERAPEUTICS INC. (INCORPORATED IN DELAWARE) (THE “NEW SUMMIT SHARES”) ON THE NASDAQ GLOBAL MARKET.

THIS DOCUMENT IS NOT A PROSPECTUS OR PROSPECTUS EQUIVALENT DOCUMENT.

Part 2 of this document comprises an explanatory statement in compliance with section 897 of the Companies Act 2006. If you are in any doubt as to the action you should take, you are recommended to seek your own personal financial advice immediately from your stockbroker, bank manager, solicitor, accountant or other independent financial adviser authorised under the Financial Services and Markets Act 2000 if you are in the United Kingdom, or other appropriately authorised independent financial adviser if you are in a territory outside the United Kingdom.

If you have sold or otherwise transferred all of your Old Summit Shares, please forward this document and the accompanying reply paid envelope (but excluding any personalised Forms of Proxy) as soon as possible to the purchaser or transferee or to the bank, stockbroker or other agent through whom the sale or transfer was effected, for delivery to the purchaser or transferee. However, such documents should not be forwarded or transmitted in or into any jurisdiction in which such act would constitute a violation of the relevant laws in such jurisdiction. If you have sold or transferred part of your holding of Old Summit Shares, please consult the bank, stockbroker or other agent through whom the sale or transfer was effected.

The distribution of this document into jurisdictions other than the United Kingdom may be restricted by the laws of those jurisdictions and therefore persons into whose possession this document comes should inform themselves about, and observe, any such restrictions. Failure to comply with any such restrictions may constitute a violation of the securities laws of any such jurisdiction.

Summit Therapeutics plc

(incorporated in England and Wales with registered number 05197494)

Recommended proposals for the introduction of a new US-incorporated

holding company to be effected by means of a Scheme of Arrangement

under Part 26 of the Companies Act 2006

Old Summit Shareholders and/or Old Summit ADS holders should read carefully the whole of this document, the information incorporated by reference into this document and the accompanying Forms of Proxy. This document is also available on the website of Old Summit at www.summitplc.com. Your attention is drawn to the letter from the Executive Chairman and Chief Executive Officer of Old Summit in Part 1 of this document which contains the unanimous recommendation of the Old Summit Directors that you vote in favour of the Scheme at the Court Meeting and the Resolutions to be proposed at the General Meeting. A statement explaining the Scheme in greater detail, which constitutes an explanatory statement in compliance with section 897 of the Companies Act 2006, appears in Part 2 of this document.

The action to be taken in respect of the Meetings is set out in paragraph 19 of Part 2 of this document. Old Summit Shareholders will find enclosed with this document a BLUE Form of Proxy for use in connection with the Court Meeting, and a WHITE Form of Proxy for use in connection with the General Meeting.

Please complete and sign both of the enclosed Forms of Proxy in accordance with the instructions printed on them and return them to Link Asset Services as soon as possible and, in any event, so as to be received at least 48 hours before the time appointed for the relevant Meeting (excluding any part of a day that is not a Business Day). Forms of Proxy returned by fax will not be accepted.

As an alternative to completing the hard copy Forms of Proxy, you can appoint a proxy electronically by visiting www.signalshares.com. You will be asked to enter your Investor Code shown on your share certificate and agree to certain terms and conditions. For an electronic proxy appointment to be valid, your appointment must be received by Link Asset Services not less than 48 hours before the time appointed for holding the relevant Meeting (excluding any part of a day that is not a Business Day).

CREST members who wish to appoint a proxy or proxies by utilising the CREST electronic appointment service, may do so for the Meetings and any adjournment(s) thereof by utilising the procedures described in the “CREST Reference Manual” issued by Euroclear UK & Ireland Limited (the “CREST Manual”). CREST personal members or other CREST sponsored members and those CREST members who have appointed (a) voting service provider(s), should refer to their CREST sponsor or voting service provider(s), who will be able to take the appropriate action on their behalf.

In light of the ongoing COVID-19 pandemic and associated difficulties with the holding of physical shareholder meetings, as permitted by the Corporate Insolvency and Governance Act 2020, the Meetings will be held by telephone. The Company will be providing a listen-only conference call facility to enable Old Summit Shareholders to follow proceedings of the Meetings remotely. All Old Summit Shareholders are encouraged to use this facility and to follow proceedings of the Meetings in real time if they wish to do so. Any Old Summit Shareholder who wishes to listen to the Meetings by such means should contact the Company prior to the day of the Meetings via email at investors@summitplc.com (including their Investor Code) in order to request dial-in details. Old Summit Shareholders using the conference call facility will not be able to vote or ask questions using this service. Accordingly, if Old Summit Shareholders wish to have their vote counted at the Meetings, they must vote by submitting their Forms of Proxy or appointing their proxy electronically (as the case may be) by the relevant time. The Meetings will end immediately after the formal business. You are therefore strongly urged to return your Forms of Proxy or appoint your proxy electronically (as the case may be), appointing the chairman of the relevant Meeting as your proxy by the relevant time. Unless the Forms of Proxy are returned by the relevant time, they will be invalid and your vote will not be counted.

If you have any questions relating to this document or the completion and return of the Forms of Proxy, please call Link Asset Services on 0371 664 0321. Calls are charged at the standard geographic rate and will vary by provider. Calls from outside the United Kingdom will be charged at the applicable international rate. The helpline is open between 9.00 a.m. – 5.30 p.m., Monday to Friday excluding public holidays in England and Wales. Please note that Link Asset Services cannot provide any financial, legal or tax advice and calls may be recorded and monitored for security and training purposes.

Registered holders of Old Summit ADSs as at the ADS Voting Record Time will be contacted by The Bank of New York Mellon as depositary for the Old Summit ADSs (the “Depositary”) with guidelines on how to provide voting instructions to the Depositary with respect to the Old Summit ADSs. In order to vote, holders of Old Summit ADSs are required to follow the voting instructions and to meet the deadlines provided by the Depositary. Persons that hold Old Summit ADSs in accounts with brokers or other securities intermediaries as at the ADS Voting Record Time should follow the instructions provided by their brokers or other securities intermediaries.

Upon effectiveness of the Scheme, it is expected that the Old Summit ADSs will be delisted and the New Summit Shares will be listed on the Nasdaq Global Market, and trading in them will commence on the Nasdaq Global Market at the opening of business (New York time) on 21 September 2020.

NO NEW SUMMIT SHARES HAVE BEEN MARKETED TO, NOR ARE ANY NEW SUMMIT SHARES AVAILABLE FOR PURCHASE BY, THE PUBLIC IN THE UNITED KINGDOM OR ELSEWHERE IN CONNECTION WITH THE INTRODUCTION OF THE NEW SUMMIT SHARES TO THE NASDAQ GLOBAL MARKET.

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THIS DOCUMENT DOES NOT CONSTITUTE AN INVITATION OR OFFER TO SELL OR EXCHANGE OR THE SOLICITATION OF AN INVITATION OR OFFER TO BUY OR EXCHANGE ANY SECURITY OR TO BECOME A STOCKHOLDER OF NEW SUMMIT. NONE OF THE SECURITIES REFERRED TO IN THIS DOCUMENT SHALL BE SOLD, ISSUED, EXCHANGED OR TRANSFERRED IN ANY JURISDICTION IN CONTRAVENTION OF APPLICABLE LAWS.

OVERSEAS SHAREHOLDERS

The release, publication or distribution of this document in certain jurisdictions may be restricted by law. Persons who are not resident in the United Kingdom or who are subject to the laws and/or regulations of another jurisdiction should inform themselves of, and should observe, any applicable requirements. Any failure to comply with these requirements may constitute a violation of the securities laws of any such jurisdiction. To the fullest extent permitted by applicable law, the companies and persons involved in the Proposals disclaim any responsibility or liability for the violation of such requirements by any person.

Unless otherwise permitted by applicable law and regulation, this document (and the matters referred to herein) will not be made available, directly or indirectly, in, into or from a jurisdiction where to do so would violate the laws in that jurisdiction, and no person may vote in favour of the Proposals by any such use, means, instrumentality or form within any jurisdiction if to do so would constitute a violation of the laws of that jurisdiction. Accordingly, copies of this document and all documents relating to the Proposals are not being, and must not be, directly or indirectly, mailed or otherwise forwarded, distributed or sent in, into or from a jurisdiction where to do so would violate the laws in that jurisdiction, and persons receiving this document and all documents relating to the Proposals (including custodians, nominees and trustees) must not mail or otherwise distribute or send them in, into or from such jurisdictions where to do so would violate the laws in that jurisdiction. Any person (including, without limitation, any custodian, nominee and trustee) who would, or otherwise intends to, or who may have a contractual or legal obligation to, forward this document and/or any other related document to any jurisdiction outside the UK should inform themselves of, and observe, any applicable legal or regulatory requirements of their jurisdiction.

The availability of this document to Old Summit Shareholders and/or Old Summit ADS holders who are not resident in the United Kingdom may be affected by the laws of the relevant jurisdictions in which they are resident (including affecting the ability of such Old Summit Shareholders to vote their Old Summit Shares and/or Old Summit ADS holders to vote their Old Summit ADSs with respect to the Scheme and the Proposals at the Meetings, or to execute and deliver Forms of Proxy appointing another to vote at the Meetings on their behalf). Persons who are not resident in the United Kingdom or who are subject to the laws and/or regulations of another jurisdiction should inform themselves of, and should observe, any applicable requirements.

Overseas Shareholders should consult their own legal and tax advisers with respect to the legal and tax consequences of the Scheme in their particular circumstances.

INFORMATION FOR UNITED STATES SHAREHOLDERS

The cancellation of the Scheme Shares and the allotment and issue of the New Summit Shares relate to shares of a UK company and a US company respectively and are proposed to be effected by means of a scheme of arrangement under the laws of England and Wales. A transaction effected by means of a scheme of arrangement is not subject to proxy solicitation or tender offer rules under the US Securities Exchange Act of 1934, as amended (the “US Exchange Act”). Accordingly, the Scheme is subject to the disclosure requirements, rules and practices applicable in the United Kingdom to schemes of arrangement, which differ from the requirements of US proxy solicitation or tender offer rules under the US Exchange Act.

The New Summit Shares will not be registered under the US Securities Act of 1933, as amended (the “US Securities Act”), or under the securities laws of any state or other jurisdiction of the United States. Accordingly, the New Summit Shares may not be offered, sold, resold, delivered, distributed or otherwise transferred, directly or indirectly, in or into the United States absent registration under the US Securities Act or pursuant to an exemption therefrom. The New Summit Shares are expected to be issued in reliance upon the exemption from the registration requirements of the US Securities Act provided by Section 3(a)(10) thereof. Shareholders who are affiliates of New Summit after the Scheme becomes Effective will be subject to certain US transfer restrictions relating to the New Summit Shares received in connection with the Scheme. Shareholders who are not affiliates of New Summit after the Scheme becomes Effective may resell their New Summit Shares without restriction under the US Securities Act.

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For the purposes of qualifying for the exemption from the registration requirements of the US Securities Act afforded by Section 3(a)(10), Old Summit will advise the Court through counsel that its sanctioning of the Scheme will be relied upon by New Summit as an approval of the Scheme following a hearing on its fairness to Old Summit Shareholders at which hearing all such Old Summit Shareholders will be entitled to attend themselves or through counsel to support or oppose the sanctioning of the Scheme and with respect to which notification has been or will be given to all such Old Summit Shareholders. In light of the ongoing COVID-19 pandemic, the Court Hearing is likely to be conducted via Skype. If you are interested in attending the Court Hearing via Skype, you are directed to the Business and Property Courts Rolls Building Cause List at justice.gov.uk for details of how to do so. The time of the Court Hearing and information on how to attend will be updated on the Court’s website after 4.30 p.m. on the Business Day before the Court Hearing.

It may be difficult for US Shareholders and US holders of Old Summit ADSs to enforce their rights and claims arising out of the US federal securities laws, since Old Summit is located in a country other than the United States. US Shareholders may not be able to sue a non-US company or its officers or directors in a non-US court for violations of the US securities laws. Further, it may be difficult to compel a non-US company and its affiliates to subject themselves to a US court’s judgment.

None of the securities referred to in this document has been approved or disapproved by the SEC, any state securities commission in the United States or any other US regulatory authority, nor have such authorities passed upon or determined the adequacy or accuracy of the information contained in this document. Any representation to the contrary is a criminal offence in the United States.

US Shareholders and US holders of Old Summit ADSs should note that no appraisal or similar rights of dissenting shareholders are to apply in connection with the Scheme as none are required as a matter of English law.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This document contains statements about Old Summit and New Summit that are or may be forward-looking statements. All statements other than statements of historical facts included in this document may be forward-looking statements. Without limitation, any statements preceded or followed by or that include the words “targets”, “plans”, “believes”, “expects”, “aims”, “intends”, “will”, “may”, “anticipates”, “estimates”, “projects” or words or terms of similar substance or the negative thereof, are forward-looking statements. Forward-looking statements include statements relating to the following: (i) expectations with respect to the timetable for completing the Scheme; (ii) potential benefits of the Scheme; (iii) future capital expenditures, expenses, revenues, earnings, synergies, economic performance, indebtedness, financial condition, dividend policy, losses and future prospects; (iv) business and management strategies and the expansion and growth of Old Summit or New Summit’s operations; and (v) the effects of Government regulation on Old Summit or New Summit’s business.

Such forward-looking statements involve risks and uncertainties that could significantly affect expected results and are based on certain key assumptions. Many factors could cause actual results to differ materially from those projected or implied in any forward-looking statements, including the factors discussed in the “Risk Factors” section of filings that Old Summit makes with the SEC, including its Transition Report on Form 20-F for the transition period from 1 February 2019 to 31 December 2019. Due to such uncertainties and risks, readers are cautioned not to place undue reliance on such forward-looking statements, which speak only as of the date hereof. Old Summit and New Summit disclaim any obligation to update any forward-looking or other statements contained herein, except as required by applicable law. Nothing in this document has been reviewed by the auditors of Old Summit or New Summit. All subsequent oral or written forward-looking statements attributable to Old Summit or New Summit or any of their respective members, directors, officers or employees or any persons acting on their behalf are expressly qualified in their entirety by the cautionary statement above. Should one or more of these risks or uncertainties materialise, or should underlying assumptions prove incorrect, actual results may vary materially from those described in this document.

Save as required by the requirements of the US Securities Act, the US Exchange Act and any other applicable US state or federal securities laws or pursuant to the rules of the Nasdaq Global Market or

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applicable law, neither Old Summit nor New Summit undertakes any obligation to publicly release the results of any revisions to any forward-looking statements in this document that may occur due to any change in the Board’s expectations or to reflect events or circumstances after the date of this document.

ROUNDING

Certain figures included in this document have been subjected to rounding adjustments.

DATE

This document is published on 27 July 2020.

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TABLE OF CONTENTS

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The following times and dates are indicative only and are subject to change⁶

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To the holders of Old Summit Shares, holders of Old Summit ADSs and, for information only, to the holders of options and awards granted under the Old Summit Share Plans and the holders of the Old Summit Warrants

Dear Shareholder,

Recommended proposals relating to the introduction of a new US-incorporated holding

company to be effected by means of a Scheme of Arrangement under Part 26 of the

Companies Act 2006

On 16 July 2020, Summit Therapeutics plc (incorporated in England and Wales) (“Old Summit”) announced its intention to put in place a new US-incorporated and domiciled holding company of the Summit Group, to be effected by way of a Court approved scheme of arrangement under sections 895 to 899 of the Companies Act (the “Scheme”), including a capital reduction. The new holding company, Summit Therapeutics Inc., is incorporated in Delaware (“New Summit”) and an application will be made, subject to the Scheme becoming Effective, for its shares of common stock to be listed on the Nasdaq Global Market. It is also intended that the Old Summit ADSs are delisted from the Nasdaq Global Market, Old Summit is re-registered as a private company and Old Summit will be renamed Summit Therapeutics Limited.

Under the Scheme, Old Summit Shareholders at the Scheme Record Time will receive, in exchange for their Old Summit Shares, New Summit Shares on the following basis:

which will result in Old Summit Shareholders holding New Summit Shares in the same proportions (save for fractional entitlements) in which they hold Old Summit Shares (or such number of Old Summit Shares as is represented by the number of Old Summit ADSs held by them) immediately prior to the Scheme Effective Date. Upon the Scheme becoming Effective, Old Summit will be a wholly-owned subsidiary of New Summit.

Old Summit Shares held in uncertificated form will be disabled in CREST on the Scheme Effective Date. Unlike Old Summit Shares, New Summit Shares are not capable of being held, transferred or settled directly through the CREST settlement system. A Scheme Shareholder who holds Scheme Shares in uncertificated form through CREST (directly or through a broker or other nominee with a CREST account) immediately prior to the Scheme Record Time will be issued New Summit Shares in the manner set out in paragraph 14 of Part 2 of this document.

Upon the Scheme becoming Effective, the existing Old Summit Shares underlying each Old Summit ADS will be cancelled and the New Summit Shares issued in exchange will be registered in the name of the

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Depositary. Persons registered as holding Old Summit ADSs at the effective date set by the Depositary will be entitled to receive one New Summit Share for every five underlying Old Summit Shares. Further details of the settlement process for holders of Old Summit ADSs is set out in paragraph 14 of Part 2 of this document.

Fractional entitlements of New Summit Shares shall not be issued and to the extent Old Summit Shareholders are entitled to fractional New Summit Shares, those fractional entitlements will be aggregated and sold in the market and the net proceeds of sale distributed pro rata to the Old Summit Shareholders entitled to them. Such payment will be made by way of cheque in pounds sterling, the applicable proceeds having been converted from US dollars at a prevailing exchange rate.

Accordingly, immediately upon the Scheme becoming Effective, a New Summit Shareholder will have the same proportionate interest in New Summit (save for fractional entitlements) as they have in Old Summit immediately prior to the Scheme Effective Date.

The Summit Group will have the same business and operations immediately after the Scheme Effective Date as Old Summit has immediately before the Scheme Effective Date.

The assets and liabilities of the Summit Group immediately after the Scheme Effective Date will not differ from the assets and liabilities of Old Summit before the Scheme Effective Date, save that New Summit will hold all of the ordinary shares then in issue in Old Summit.

A number of differences exist between the Old Summit Articles and the New Summit Certificate of Incorporation and the New Summit Bylaws, arising as a consequence of New Summit being a company incorporated in Delaware and not in England and Wales (which means that New Summit will be subject to the laws of Delaware).

A summary of the principal differences between the rights of the Old Summit Shareholders and New Summit Shareholders is contained in paragraph 1 of Part 3 of this document.

The purpose of this document is to explain the Proposals to you and why the Old Summit Directors consider the Proposals to be in the best interests of Old Summit and its shareholders as a whole.

The Old Summit Directors are unanimously recommending that you vote in favour of the Proposals as they intend to do in respect of their aggregate shareholdings in Old Summit representing 62.8 per cent. of the total voting rights in Old Summit as at the Latest Practicable Date.

A summary of the action recommended to be taken is set out in paragraph 5 of this Part and on the Forms of Proxy.

Old Summit Shareholders should read the whole of this document and not only rely on the summarised information set out in this letter. Old Summit Shareholders will find definitions for capitalised terms used in this letter and the rest of this document in Part 7 of this document.

Old Summit is a biopharmaceutical company focussed on the discovery, development and commercialisation of novel antibiotics for the treatment of serious infectious diseases. Old Summit’s most advanced product candidate is ridinilazole (formerly SMT19969), an orally administered small molecule antibiotic for the potential front-line treatment of infections caused by the bacteria, Clostridioides difficile or C. difficile. Ridinilazole is currently being evaluated in a global Phase 3 clinical trial programme called Ri-CoDIFy that has been designed to support potential adoption of ridinilazole as the new standard of care treatment for C. difficile infection (“CDI”).

Old Summit is also developing a pipeline of new classes of antibiotics using its proprietary Discuva Platform. The Discuva Platform is utilised from discovery through the selection of optimised clinical candidates. Old Summit believes that the Discuva Platform has the potential to deliver antibiotics with new mechanisms of action, a targeted spectrum of activity and a low likelihood of developing drug resistance. Old Summit is currently developing early-stage programmes targeting infections caused by the bacteria Enterobacteriaceae and Neisseria gonorrhoeae.

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Old Summit was incorporated as a public limited company under the laws of England and Wales in 2004.

In recent years however, Old Summit’s business operations have increasingly focussed on the United States, one of the world’s most important pharmaceutical markets. This is evidenced by the location of the trading on the public equity markets of Old Summit ADSs, its growing physical presence in the United States, the location of its central management and control and its emerging commercial strategy for marketing its investigational antibiotic therapies.

Old Summit became a publicly listed company in the United Kingdom in October 2014 following the commencement of trading of Old Summit Shares on the AIM market of the London Stock Exchange. In March 2015, Old Summit completed its initial public offering of ADSs on the Nasdaq Global Market, with one Old Summit ADS representing five Old Summit Shares. In February 2020, Old Summit cancelled the admission of its Old Summit Shares to trading on AIM meaning that Old Summit Shares are now traded exclusively on the Nasdaq Global Market in the form of the Old Summit ADSs.

Since Old Summit was incorporated, its principal office has been in Oxfordshire, United Kingdom. Over recent years, the business has increasingly focussed its operations on the United States. In 2014, physical operations in the United States were established following the opening of an office in Cambridge, Massachusetts. The operations of Old Summit in the United States are conducted through its wholly-owned subsidiary, Summit Therapeutics Sub Inc (formerly Summit Therapeutics Inc.), which was incorporated in Delaware in 2014. The workforce of Old Summit in the United States provides support across a range of business functions including clinical operations, regulatory development, commercial, finance and investor relations.

In December 2019, Old Summit’s place of central management and control moved from the United Kingdom to the United States following a restructuring of the Board. Specifically, four new non-executive directors were appointed, including Mr Robert Duggan, the principal shareholder of Old Summit who is based in the United States, to replace the three previous non-executive directors. This resulted in the majority of the Board residing in the United States. In April 2020, Mr Duggan was appointed to the role of Executive Chairman and Chief Executive Officer and an additional United States based non-executive director was appointed. As of June 2020, one of the four new non-executive directors appointed in December 2019 no longer serves on the Board. In July an additional non-executive director was appointed.

During the first half of 2020 the executive management of Old Summit transitioned from being based in the United Kingdom to the majority of roles now being based in the United States, including the positions of Chief Executive Officer and Chief Financial Officer.

Old Summit holds exclusive commercialisation rights for ridinilazole for all indications in the United States. If ridinilazole receives marketing approval from the US regulatory authority, the US Food and Drug Administration, Old Summit plans to commercialise it in the United States with its own focussed, specialised sales force. Old Summit retains exclusive commercial rights in other territories, including Europe and Asia, and has granted exclusive rights to commercialise ridinilazole in certain countries in South America, Central America and the Caribbean to Eurofarma Laboratorios.

The Board expects its US business operations will continue to expand as it prepares for the potential commercial launch of ridinilazole for the treatment of CDI in the US. The Board believes that Old Summit redomiciling as described within this document will enable the business to execute on its business strategy more effectively for the benefit of all stakeholders for the following reasons:

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There are currently no plans to relocate the existing subsidiary companies of Old Summit that are incorporated in England and Wales. This includes the two trading companies, Summit (Oxford) Limited and Discuva Limited.

Under the Scheme, New Summit will issue New Summit Shares to Scheme Shareholders in the ratio set out in paragraph 1 of this Part in consideration for the cancellation of the Scheme Shares and the issue of New Ordinary Shares to New Summit.

Following the cancellation of the Scheme Shares, the reserve arising in the books of account of Old Summit as a result of such cancellation shall be capitalised and applied in paying up in full at par such number of New Ordinary Shares as shall be equal to the number of Scheme Shares cancelled. The New Ordinary Shares will be issued to New Summit which will, as a result, hold all of the Old Summit Shares then in issue. New Summit will in turn issue New Summit Shares to former Old Summit Shareholders on a one-for-five basis.

The New Summit Shares to be issued pursuant to the Scheme will have a par value of US$0.01 each.

Immediately following the Scheme becoming Effective, New Summit shall cancel the New Summit Initial Shares, so as to ensure that, following the completion of the cancellation, each Old Summit Shareholder and each holder of Old Summit ADSs will hold New Summit Shares in the same proportions (save for fractional entitlements) in which they hold Old Summit Shares (or such number of Old Summit Shares as is represented by the number of Old Summit ADSs held by them) immediately prior to the Scheme Effective Date.

New Summit is a corporation incorporated in Delaware and was incorporated specifically for the purpose of implementing the Proposals. New Summit has not traded prior to the date of this document or entered into any obligations (except for entering into transactions relating to the Scheme and the Proposals).

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Application will be made for the New Summit Shares to be listed on the Nasdaq Global Market. It is expected that listing on the Nasdaq Global Market of New Summit Shares will become Effective and that dealings will commence at 9.30 a.m. (New York time) on 21 September 2020.

The last day of dealings in Old Summit ADSs is expected to be 17 September 2020. The last time for registration of transfers of Old Summit Shares is expected to be 5.00 p.m. on 17 September 2020 and 5.00 p.m. (New York time) on 17 September 2020 in respect of the Old Summit ADSs.

These dates may be deferred if it is necessary to adjourn any meetings required to approve the arrangements described in this document or if there is any delay in obtaining the Court’s sanction of the Scheme or its confirmation of the Old Summit Reduction of Capital. In the event of a delay, the application for the Old Summit ADSs to be delisted will be deferred, so that the listing will not be cancelled until immediately before the Scheme takes effect.

Participants in the Old Summit Share Plans and holders of Old Summit Warrants will receive further details of the effect of the Proposals on their outstanding options, awards and warrants in separate letters which will be despatched to them in due course, as set out in paragraph 9 of Part 2 of this document.

Details of the New Summit Share Plans that have been adopted by New Summit and which Old Summit Shareholders are being asked to approve at the General Meeting, are set out in paragraph 2 of Part 3 of this document.

New Summit is seeking approval of the New Summit Share Plans by the Old Summit Shareholders in an effort to ensure that the New Summit Share Plans satisfy the requirements of the listing rules of the Nasdaq Global Market, without the cost and delay that a separate meeting of New Summit’s stockholders following the Scheme Effective Date would incur.

The Scheme will not be implemented unless certain approvals are obtained, including the approval of the Scheme by the Scheme Shareholders at the Court Meeting, the approval by the Old Summit Shareholders of the Special Resolution required in connection with the Scheme at the General Meeting and the sanction of the Court. The Court Meeting and the General Meeting have been convened for 1.30 p.m. and 1.40 p.m. respectively on 19 August 2020.

A full explanation of the Scheme is contained in the explanatory statement in Part 2 of this document. Among other things, Part 2 of this document explains certain proposals relating to the treatment of Overseas Shareholders.

Your attention is drawn to the general guidance on the tax position of Old Summit Shareholders set out in paragraph 3 of Part 3 of this document.

Paragraph 3 of Part 3 of this document is intended as a guide only and any Old Summit Shareholders who are in any doubt as to their tax position, or who are resident for tax purposes outside of the United Kingdom are strongly advised to consult an appropriate independent professional adviser.

The Scheme requires approval by a simple majority in number representing not less than 75 per cent. of the nominal value of the Old Summit Shares of those Old Summit Shareholders present and voting (either in person or by proxy) at the Court Meeting. The passing of the Special Resolution at the General Meeting is also required to effect the Scheme.

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The implementation of the Old Summit Reduction of Capital will require the passing of the Special Resolution by the Old Summit Shareholders at the General Meeting.

The implementation of the New Summit Share Plans by New Summit immediately on the Scheme Effective Date will require the passing of the New Summit Share Plans Resolutions.

Further particulars of the Court Meeting and the General Meeting are contained in the explanatory statement in Part 2 of this document.

In addition, the Scheme requires the sanction of the Court and the Old Summit Reduction of Capital requires the confirmation of the Court. The Court Hearing to approve the Scheme and the Old Summit Reduction of Capital is expected to be held on 16 September 2020.

You will find enclosed with this document:

IT IS IMPORTANT THAT, FOR THE COURT MEETING IN PARTICULAR, AS MANY VOTES AS POSSIBLE ARE CAST SO THAT THE COURT MAY BE SATISFIED THAT THERE IS A FAIR AND REASONABLE REPRESENTATION OF OLD SUMMIT SHAREHOLDER OPINION. YOU ARE THEREFORE STRONGLY ENCOURAGED TO SIGN AND RETURN YOUR FORMS OF PROXY AS SOON AS POSSIBLE.

IN LIGHT OF THE ONGOING COVID-19 PANDEMIC AND ASSOCIATED DIFFICULTIES WITH THE HOLDING OF PHYSICAL SHAREHOLDER MEETINGS, AS PERMITTED BY THE CORPORATE INSOLVENCY AND GOVERNANCE ACT 2020, THE MEETINGS WILL BE HELD BY TELEPHONE. THE COMPANY WILL BE PROVIDING A LISTEN-ONLY CONFERENCE CALL FACILITY TO ENABLE OLD SUMMIT SHAREHOLDERS TO FOLLOW PROCEEDINGS OF THE MEETINGS REMOTELY. ALL OLD SUMMIT SHAREHOLDERS ARE ENCOURAGED TO USE THIS FACILITY AND TO FOLLOW PROCEEDINGS OF THE MEETINGS IN REAL TIME IF THEY WISH TO DO SO. ANY OLD SUMMIT SHAREHOLDER WHO WISHES TO LISTEN TO THE MEETINGS BY SUCH MEANS SHOULD CONTACT THE COMPANY PRIOR TO THE DAY OF THE MEETINGS VIA EMAIL AT INVESTORS@SUMMITPLC.COM (INCLUDING THEIR INVESTOR CODE) IN ORDER TO REQUEST DIAL-IN DETAILS. OLD SUMMIT SHAREHOLDERS USING THE CONFERENCE CALL FACILITY WILL NOT BE ABLE TO VOTE OR ASK QUESTIONS USING THIS SERVICE. ACCORDINGLY, IF OLD SUMMIT SHAREHOLDERS WISH TO HAVE THEIR VOTE COUNTED AT THE MEETINGS, THEY MUST VOTE BY SUBMITTING THEIR FORMS OF PROXY OR APPOINTING THEIR PROXY ELECTRONICALLY (AS THE CASE MAY BE) BY THE RELEVANT TIME. THE MEETINGS WILL END IMMEDIATELY AFTER THE FORMAL BUSINESS. YOU ARE THEREFORE STRONGLY URGED TO RETURN YOUR FORMS OF PROXY OR APPOINT YOUR PROXY ELECTRONICALLY (AS THE CASE MAY BE), APPOINTING THE CHAIRMAN OF THE RELEVANT MEETING AS YOUR PROXY BY THE RELEVANT TIME. UNLESS THE FORMS OF PROXY ARE RETURNED BY THE RELEVANT TIME, THEY WILL BE INVALID AND YOUR VOTE WILL NOT BE COUNTED.

You are requested to complete, sign and return the Forms of Proxy as soon as possible and in any event at least 48 hours before the time fixed for the relevant Meeting (excluding any part of the day that is not a Business Day). If you hold your Old Summit Shares in uncertificated form and wish to appoint a proxy through the CREST electronic proxy appointment service, please read the notes to the notices of the Court Meeting and General Meeting in Parts 5 and 6 of this document for further details.

Registered holders of Old Summit ADSs as at the ADS Voting Record Time will be contacted by the Depositary for the Old Summit ADSs with guidelines on how to provide voting instructions to the Depositary with respect to the Old Summit ADSs. In order to vote, holders of Old Summit ADSs are required to follow

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the voting instructions and to meet the deadlines provided by the Depositary. Persons that hold Old Summit ADSs in accounts with brokers or other securities intermediaries as at the ADS Voting Record Time should follow the instructions provided by their brokers or other securities intermediaries.

If you are a citizen, resident or national of a jurisdiction outside the United Kingdom, your attention is drawn to paragraph 12 of Part 2 of this document for further details concerning the Scheme.

The Board considers the Proposals and their terms to be fair and reasonable and in the best interests of shareholders of Old Summit as a whole and accordingly, the Board unanimously recommends Old Summit Shareholders and holders of Old Summit ADSs to vote in favour of the Scheme at the Court Meeting and to vote in favour of the Resolutions proposed at the General Meeting, as the Old Summit Directors intend to do in respect of their own beneficial holdings of Old Summit Shares, being in aggregate 211,197,885 Old Summit Shares, which represent approximately 62.8 per cent. of the issued Old Summit Shares as at the Latest Practicable Date, and which represents approximately 62.8 per cent. of the votes attached to Old Summit Shares in issue on the Latest Practicable Date that could be cast at the Meetings.

Your attention is drawn to:

Yours faithfully,

Robert W. Duggan

Executive Chairman and Chief Executive Officer

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PART 2

EXPLANATORY STATEMENT

(IN COMPLIANCE WITH SECTION 897 OF THE COMPANIES ACT 2006)

27 July 2020

To the holders of Old Summit Shares, holders of Old Summit ADSs and, for information only, to the holders of options and awards granted under the Old Summit Share Plans and the holders of the Old Summit Warrants

Recommended proposals relating to the introduction of a new US-incorporated holding company to be effected by means of a Scheme of Arrangement under Part 26 of the Companies Act 2006

On 16 July 2020, Old Summit announced its intention to put in place a new US-incorporated and domiciled holding company, New Summit, to be effected by way of a High Court approved scheme of arrangement under sections 895 to 899 of the Companies Act (the “Scheme”), including a capital reduction. The Scheme is subject to various conditions and, once satisfied and the Scheme is approved and implemented in full, New Summit will own the entire issued ordinary share capital of Old Summit and each Old Summit Shareholder will hold New Summit Shares in the same proportions in which they hold Old Summit Shares (save for fractional entitlements) immediately prior to the Scheme Effective Date. Holders of Old Summit ADSs will own the same proportion of New Summit Shares immediately after the Scheme Effective Date as they held in the ordinary share capital of Old Summit by virtue of their Old Summit ADSs immediately prior to the Scheme Effective Date. It is also intended that the Old Summit ADSs are delisted from the Nasdaq Global Market, Old Summit is re-registered as a private company and Old Summit will be renamed Summit Therapeutics Limited.

Your attention is drawn to the letter from the Executive Chairman and Chief Executive Officer of Old Summit in Part 1 of this document setting out the background to and reasons for the Proposals.

The Board unanimously recommends that all Old Summit Shareholders and all holders of Old Summit ADSs vote in favour of the Scheme itself at the Court Meeting and the Resolutions to be proposed at the General Meeting as the Old Summit Directors intend to do in respect of their own beneficial holdings of Old Summit Shares, being in aggregate 211,197,885 Old Summit Shares.

The details of the Scheme are set out in Part 4 of this document. The notice of the Court Meeting at which approval for the Scheme will be sought and the notice of the General Meeting at which the Resolutions will be proposed are set out in Part 5 and Part 6 of this document respectively.

The background to and reasons for the Proposals are set out in paragraph 2 of the letter from the Executive Chairman and Chief Executive Officer of Old Summit in Part 1 of this document.

The principal steps involved in the Scheme are as follows:

Under the Scheme, all the Scheme Shares will be cancelled on the Scheme Effective Date (which is expected to be 18 September 2020). In consideration for the cancellation of the Scheme Shares, the Scheme Shareholders will receive, in respect of any Scheme Shares held as at the Scheme Record Time:

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for every five Old Summit Shares one New Summit Share

Upon the Scheme becoming Effective a New Summit Shareholder will have the same proportionate interest in New Summit (save for fractional entitlements) as they have in Old Summit immediately prior to the Scheme becoming Effective.

The Summit Group will have the same business and operations immediately after the Scheme Effective Date as Old Summit has immediately before the Scheme Effective Date. The assets and liabilities of the Summit Group immediately after the Scheme Effective Date will not differ from the assets and liabilities Old Summit had before the Scheme Effective Date, save that New Summit will hold all of the ordinary shares then in issue in Old Summit.

A summary of the principal differences between the rights of Old Summit Shareholders and New Summit Shareholders is set out in paragraph 1 of Part 3 of this document.

Following the cancellation of the Scheme Shares, the reserve arising in the books of account of Old Summit as a result of such cancellation shall be capitalised and applied in paying up in full at par such number of New Ordinary Shares as shall be equal to the number of Scheme Shares cancelled. The New Ordinary Shares will be issued to New Summit which will, as a result, hold all of the ordinary shares then in issue in Old Summit. New Summit will in turn issue New Summit Shares to former Old Summit Shareholders on a one-for-five basis.

The New Summit Shares to be issued pursuant to the Scheme will have a par value of US$0.01 each.

The Board will not take the necessary steps to implement the Scheme unless the above conditions have been satisfied.

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The Scheme contains a provision for Old Summit and New Summit jointly to consent on behalf of all persons concerned to any modification of, or addition to, the Scheme, or to any condition which the Court may think fit to approve or impose. Old Summit has been advised by its legal advisers that the Court would be unlikely to approve or impose any modification of, or addition or condition to, the Scheme which might be material to the interests of Old Summit Shareholders unless Old Summit Shareholders were informed of any such modification, addition or condition. If the Court does approve or impose a modification of, or addition or condition to, the Scheme which in the opinion of the Old Summit Directors, is such as to require consent of the Old Summit Shareholders, the Old Summit Directors will not take the necessary steps to enable the Scheme to become Effective unless and until such consent is obtained.

The full text of the Scheme and the resolution to be proposed at the Court Meeting and the Special Resolution to be proposed at the General Meeting, are set out in Parts 4, 5 and 6 of this document respectively.

The Scheme will require the approval of the Scheme Shareholders at the Court Meeting, convened pursuant to an order of the Court and the passing by Old Summit Shareholders of the Special Resolution specified in the notice of the General Meeting. Both of the Meetings have been convened for 19 August 2020.

The Scheme also requires a separate sanction from the Court and the Old Summit Reduction of Capital requires confirmation from the Court. Notices of the Court Meeting and the General Meeting are contained in Parts 5 and 6 of this document respectively. New Summit has agreed to appear by Counsel at the Court Hearing and to undertake to be bound by the Scheme.

Entitlements to attend and vote at the Meetings and the number of votes which may be cast at them will be determined by reference to holdings of Old Summit Shares as shown in the register of members of Old Summit at the Voting Record Time.

The Court Meeting has been convened for 1.30 p.m. on 19 August 2020 pursuant to an order of the Court. At the Court Meeting, or at any adjournment thereof, the Old Summit Shareholders (including as instructed by holders of Old Summit ADSs) will consider and, if thought fit, approve the Scheme (with or without modification).

Voting will be by poll at the Court Meeting and each Old Summit Shareholder entitled to attend and who is present by proxy will be entitled to one vote for each Old Summit Share held. The statutory majority required to approve the Scheme at the Court Meeting is a simple majority in number representing not less than 75 per cent. of the nominal value of the Scheme Shares of the Scheme Shareholders present and voting (in person or by proxy) at the Court Meeting.

It is important that as many votes as possible are cast (in person or by proxy) at the Court Meeting so that the Court may be satisfied that there is a fair and reasonable representation of Scheme Shareholder opinion.

You are therefore strongly encouraged to complete and return the BLUE Form of Proxy or lodge an electronic proxy instruction for the Court Meeting as soon as possible and, in any event, so as to be received by 1.30 p.m. on 17 August 2020.

Registered holders of Old Summit ADSs as at the ADS Voting Record Time will be contacted by the Depositary for the Old Summit ADSs with guidelines on how to provide voting instructions to the Depositary with respect to the Old Summit ADSs. In order to vote, holders of Old Summit ADSs are required to follow the voting instructions and to meet the deadlines provided by the Depositary. Persons that hold Old Summit ADSs in accounts with brokers or other securities intermediaries as at the ADS Voting Record Time should follow the instructions provided by their brokers or other securities intermediaries.

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It is also particularly important for you to be aware that if the Scheme becomes Effective, it will be binding on all Scheme Shareholders irrespective of whether they attended (in person or by proxy) the Court Meeting (by proxy) and irrespective of the manner in which they voted.

The General Meeting has been convened for 1.40 p.m. on 19 August 2020 (or as soon thereafter as the Court Meeting concludes or is adjourned). At the General Meeting, or at any adjournment thereof, Old Summit Shareholders will consider and, if thought fit, pass the Special Resolution and the New Summit Share Plans Resolutions set out in the notice of the General Meeting contained in Part 6 of this document.

The Special Resolution set out in the notice of the General Meeting is proposed in order to:

The majority required for the passing of the Special Resolution is not less than 75 per cent. of the votes cast.

New Summit is seeking approval of the New Summit Share Plans by the Old Summit Shareholders at the General Meeting in an effort to ensure that the New Summit Share Plans satisfy the requirements of the listing rules of the Nasdaq Global Market, without the cost and delay that a separate meeting of New Summit’s stockholders following the Scheme Effective Date would incur. The New Summit Share Plans Resolutions are set out in the notice of General Meeting.

A simple majority of the votes cast is required for the passing of the New Summit Share Plans Resolutions.

All resolutions at the General Meeting will be voted on a poll.

It is proposed that the Old Summit Articles be amended so as to ensure that any Old Summit Shares which are issued after the General Meeting but prior to the Scheme Record Time will be subject to and bound by the Scheme. Any Old Summit Shares issued on the exercise of options, awards or warrants under the Old Summit Share Plans or the Old Summit Warrants, or otherwise, after the Scheme Record Time will not be subject to the Scheme. Accordingly, it is also proposed that the Old Summit Articles be amended so that any Old Summit Shares issued to any person other than New Summit on or after the Scheme Record Time will be transferred automatically to New Summit (or as it may direct) in consideration for the issue of one New Summit Share for every five Old Summit Shares so issued.

The amendments to the Old Summit Articles will also authorise Old Summit to procure the transfer of Old Summit Shares held by Overseas Shareholders to a nominee in certain circumstances.

The proposed amendments to the Old Summit Articles are set out in full in the notice of the General Meeting in Part 6 of this document.

Approval will also be sought from the Old Summit Shareholders at the General Meeting for the adoption of the New Summit Share Plans.

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Details of the New Summit Share Plans that have been adopted by New Summit and which Old Summit Shareholders are being asked to approve at the General Meeting, are set out in paragraph 2 of Part 3 of this document.

New Summit is seeking approval of the New Summit Share Plans by the Old Summit Shareholders at the General Meeting in an effort to ensure that the New Summit Share Plans satisfy the requirements of the listing rules of the Nasdaq Global Market, without the cost and delay that a separate meeting of New Summit’s stockholders following the Scheme Effective Date would incur.

The effect of full implementation of the Proposals will be as follows:

Old Summit Shares held in uncertificated form will be disabled in CREST on the Scheme Effective Date. Unlike Old Summit Shares, New Summit Shares are not capable of being held, transferred or settled directly through the CREST settlement system. A Scheme Shareholder who holds Scheme Shares in uncertificated form through CREST (directly or through a broker or other nominee with a CREST account) immediately prior to the Scheme Record Time will be issued New Summit Shares in the manner set out in paragraph 14 of this Part.

The Scheme will affect participants of the Old Summit Share Plans and the holders of the Old Summit Warrants. It is proposed by the boards of directors of each of Old Summit and New Summit that options and awards outstanding under the Old Summit Share Plans and the Old Summit Warrants at the Scheme Effective Date will be replaced with equivalent options, awards and warrants that relate to New Summit Shares. Further details of these arrangements will be communicated to participants of the Old Summit Share Plans and holders of the Old Summit Warrants in due course. Options, awards and warrants which are exercised prior to the Scheme Record Time will be satisfied by the allotment, issue or transfer of Old Summit Shares and these Old Summit Shares will be subject to the Scheme.

Your attention is drawn to the general guidance on the tax position of Old Summit Shareholders set out in paragraph 3 of Part 3 of this document.

Paragraph 3 of Part 3 of this document is intended as a guide only and any Old Summit Shareholders who are in any doubt as to their tax position, or who are resident for tax purposes outside of the United Kingdom are strongly advised to consult an appropriate independent professional adviser immediately.

A number of differences exist between the Old Summit Articles and the New Summit Certificate of Incorporation and the New Summit Bylaws, arising as a consequence of New Summit being a corporation incorporated in Delaware and not in England and Wales (which means that New Summit will be subject to the laws of Delaware).

A summary of the principal differences between the rights of Old Summit Shareholders and New Summit Shareholders is contained in paragraph 1 of Part 3 of this document.

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The release, publication or distribution of this document in jurisdictions other than the United Kingdom may be restricted by the laws of those jurisdictions and therefore persons who are subject to the laws of any jurisdiction other than the United Kingdom into whose possession this document comes should inform themselves about and observe such restrictions. Any failure to comply with any such restrictions may constitute a violation of the securities laws of any such jurisdiction.

If, in respect of any Scheme Shareholder with a registered address in a jurisdiction outside the United Kingdom or whom Old Summit reasonably believes to be a citizen, resident or national of a jurisdiction outside the United Kingdom, Old Summit is advised that the allotment and/or issue of New Summit Shares, would or may infringe the laws of such jurisdiction or would or may require Old Summit or New Summit to comply with any governmental or other consent or any registration, filing or other formality with which Old Summit or New Summit is unable to comply or compliance with which Old Summit or New Summit regards as unduly onerous, then Old Summit may, in its sole discretion, exercise its authority under its articles of association to appoint any person to execute as transferor an instrument of transfer transferring, prior to the Scheme Record Time, the Scheme Shares held by such holder to a nominee to hold such Scheme Shares on trust for that holder, on terms that the nominee shall sell the New Summit Shares, if any, that it receives pursuant to the Scheme in respect of such Scheme Shares as soon as practicable following the Scheme Effective Date.

This document and the accompanying documents have been prepared in connection with proposals in relation to a scheme of arrangement pursuant to and for the purpose of complying with English law and information disclosed may not be the same as that which would have been prepared in accordance with the laws of jurisdictions outside England and Wales. Nothing in this document or the accompanying documents should be relied on for any other purpose.

Overseas Shareholders should consult their own legal and tax advisers with respect to the legal and tax consequences of the Scheme in their particular circumstances.

THIS DOCUMENT DOES NOT CONSTITUTE AN INVITATION OR OFFER TO SELL OR EXCHANGE OR THE SOLICITATION OF AN INVITATION OR OFFER TO BUY OR EXCHANGE ANY SECURITY OR TO BECOME A MEMBER OF NEW SUMMIT. NONE OF THE SECURITIES REFERRED TO IN THIS DOCUMENT SHALL BE SOLD, ISSUED, EXCHANGED OR TRANSFERRED IN ANY JURISDICTION IN CONTRAVENTION OF APPLICABLE LAWS.

Overseas Shareholders should consult their own legal and tax advisers with respect to the legal and tax consequences of the Scheme in their particular circumstances.

Information for United States Shareholders

The cancellation of the Scheme Shares and the allotment and issue of the New Summit Shares relate to shares of a UK company and a US company respectively and are proposed to be effected by means of a scheme of arrangement under the laws of England and Wales. A transaction effected by means of a scheme of arrangement is not subject to proxy solicitation or tender offer rules under the US Exchange Act. Accordingly, the Scheme is subject to the disclosure requirements, rules and practices applicable in the United Kingdom to schemes of arrangement, which differ from the requirements of US proxy solicitation or tender offer rules under the US Exchange Act.

The New Summit Shares will not be registered under the US Securities Act or under the securities laws of any state or other jurisdiction of the United States. Accordingly, the New Summit Shares may not be offered, sold, resold, delivered, distributed or otherwise transferred, directly or indirectly, in or into the United States absent registration under the US Securities Act or pursuant to an exemption therefrom. The New Summit Shares are expected to be issued in reliance upon the exemption from the registration requirements of the US Securities Act provided by Section 3(a)(10) thereof. Shareholders who are affiliates of New Summit after the Scheme becomes Effective will be subject to certain US transfer restrictions relating to the New Summit Shares received in connection with the Scheme. Shareholders who are not affiliates of New Summit after the Scheme becomes Effective may resell their New Summit Shares without restriction under the US Securities Act.

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For the purposes of qualifying for the exemption from the registration requirements of the US Securities Act afforded by Section 3(a)(10), Old Summit will advise the Court through counsel that its sanctioning of the Scheme will be relied upon by New Summit as an approval of the Scheme following a hearing on its fairness to Old Summit Shareholders.

None of the securities referred to in this document has been approved or disapproved by the SEC, any state securities commission in the United States or any other US regulatory authority, nor have such authorities passed upon or determined the adequacy or accuracy of the information contained in this document. Any representation to the contrary is a criminal offence in the United States.

US Shareholders should note that no appraisal or similar rights of dissenting shareholders are to apply in connection with the Scheme as none are required as a matter of English law.

Old Summit Shareholders who are citizens or residents of the US should consult their own legal and tax advisers with respect to the legal and tax consequences of the Scheme and in their particular circumstances.

Enforceability of judgments

It may be difficult for US Shareholders to enforce their rights and claims arising out of the US federal securities laws, since Old Summit is located in a country other than the United States. US Shareholders may not be able to sue a non-US company or its officers or directors in a non-US court for violations of the US securities laws. Further, it may be difficult to compel a non-US company and its affiliates to subject themselves to a US court’s judgment.

Application will be made for the New Summit Shares to be listed on the Nasdaq Global Market under the symbol “SMMT”. It is expected that when the New Summit Shares will be issued, their listing will become effective and that dealings will commence on 21 September 2020.

If all the conditions to the Scheme are satisfied, Old Summit intends to seek the delisting of the Old Summit ADSs from the Nasdaq Global Market with effect from the Scheme Effective Date. The last day of dealings in Old Summit ADSs is expected to be 17 September 2020. The last time for registration of transfers of Old Summit Shares is expected to be 5.00 p.m. on 17 September 2020 and 5.00 p.m. (New York time) on 17 September 2020 in respect of Old Summit ADSs.

These dates may be deferred if it is necessary to adjourn any meetings required to approve the Scheme as described in this document or there is any delay in obtaining the Court’s sanction of the Scheme or the Old Summit Reduction of Capital. In the event of a delay, the application for cancellation of the Old Summit ADSs will be deferred so that the admission of the Old Summit ADSs will not be cancelled until immediately prior to the Scheme Effective Date.

On the Scheme Effective Date, all certificates representing Old Summit Shares will cease to be valid and binding in respect of such holdings and should be destroyed.

As soon as practicable and, in any event, no later than 14 days after the Effective Date, Computershare will mail a statement by first class mail to each Scheme Shareholder holding Scheme Shares in certificated form providing evidence of ownership of the New Summit Shares such Scheme Shareholder holds. Such Scheme Shareholders wishing to deposit their New Summit Shares electronically with DTC will need to contact their brokers to arrange for deposit of those shares following receipt of their statement providing evidence of ownership. Temporary documents of title will not be issued and transfer of New Summit Shares by such Scheme Shareholders will not be permitted until they receive their statement providing evidence of ownership and effect such transfer in accordance with the directions on such statement.

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Accordingly, holders of Scheme Shares in certificated form should be aware that there will be a delay in their ability to deal with their New Summit Shares until after they receive their statement providing evidence of ownership.

Old Summit Shares held in uncertificated form will be disabled in CREST on the Scheme Effective Date.

Unlike Old Summit Shares, New Summit Shares are not capable of being held, transferred or settled directly through the CREST settlement system. A Scheme Shareholder who holds Scheme Shares in uncertificated form through CREST (directly or through a broker or other nominee with a CREST account) immediately prior to the Scheme Record Time will be issued New Summit Shares in the manner described below.

As soon as practicable and, in any event, no later than 14 days after the Effective Date, Computershare will mail a statement by first class mail to each Scheme Shareholder holding Scheme Shares in uncertificated form providing evidence of ownership of the New Summit Shares such Scheme Shareholder holds. Such Scheme Shareholders wishing to deposit their New Summit Shares electronically with DTC will need to contact their brokers to arrange for deposit of those shares following receipt of their statement providing evidence of ownership. Temporary documents of title will not be issued and transfer of New Summit Shares by such Scheme Shareholders will not be permitted until they receive their statement providing evidence of ownership and effect such transfer in accordance with the directions on such statement.

Accordingly, holders of Scheme Shares in uncertificated form should be aware that there will be a delay in their ability to deal with their New Summit Shares until after they receive their statement providing evidence of ownership.

In connection with the cancellation of the Scheme Shares and the issue of the Old Summit Shares to New Summit, the ADS facility which is currently in place in the US in respect of the Old Summit Shares will be terminated. The Old Summit ADS facility will not be replicated by New Summit.

Upon the Scheme becoming Effective, the existing Old Summit Shares underlying each Old Summit ADS will be cancelled and New Summit Shares issued in exchange will be registered in the name of the Depositary. Persons registered as holding Old Summit ADSs at the effective date set by the Depositary will be entitled to receive one New Summit Share for every five underlying Old Summit Shares.

Holders of Old Summit ADSs at the effective date set by the Depositary will own the same proportion of common stock of New Summit immediately after the Scheme Effective Date as they held in the ordinary share capital of Old Summit by virtue of their Old Summit ADSs immediately prior to the Scheme Effective Date.

The Depositary will send a notice to any registered holders of Old Summit ADSs that are evidenced by certificates (American Depositary Receipts) regarding the mechanics of surrendering their Old Summit ADSs for cancellation for delivery of New Summit Shares. Holders of certificated Old Summit ADSs will need to follow the instructions set out in that notice to surrender their Old Summit ADSs for cancellation and to receive the New Summit Shares. Registered holders of uncertificated Old Summit ADSs will have New Summit Shares registered in their names and their Old Summit ADSs will be cancelled. Those holders do not need to take any action.

To the extent Old Summit ADSs are held through a bank, broker or other securities intermediary holding Old Summit ADSs in DTC, the Depositary will arrange for DTC to surrender its entire position of Old Summit ADSs for cancellation and the Depositary will deliver New Summit Shares through the DTC settlement system, in each case with no action being required on the part of the persons holding those Old Summit ADSs.

In accordance with the terms of the Deposit Agreement, holders of Old Summit ADSs will be charged a fee of US$0.05 for each Old Summit ADS (or a portion thereof) cancelled.

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All instructions in force at the Scheme Effective Date relating to notices and other communications will, unless and until varied or revoked, be deemed from the Scheme Effective Date to be valid and effective mandates or instructions to New Summit in relation to the corresponding holding of New Summit Shares. However, the Old Summit ADS facility will not be replicated by New Summit.

Fractional entitlements of New Summit Shares shall not be issued and to the extent Old Summit Shareholders are entitled to fractional New Summit Shares, those fractional entitlements will be aggregated and sold in the market and the net proceeds of sale distributed pro rata to the Old Summit Shareholders entitled to them. Such payment will be made by way of cheque in pounds sterling, the applicable proceeds having been converted from US dollars at a prevailing exchange rate.

The holder of the New Summit Initial Shares has already approved, among other matters:

All of the Board will have been appointed directors of New Summit as of the Scheme Effective Date.

The effect of the Scheme on the interests of the Old Summit Directors (details of which are set out in paragraph 17 below) does not differ from its effect on the like interests of other persons. Old Summit Shareholders are, however, referred to the matters described in paragraph 1 of Part 3 of this document in relation to the effect on the Old Summit Directors (in their capacity as directors) arising from the differences between the Old Summit Articles and the New Summit Certificate of Incorporation and New Summit Bylaws and the fact that New Summit is incorporated in Delaware.

After the Scheme Effective Date, the Board will receive their remuneration from New Summit and the total emoluments receivable by each of those members of the Board will not be materially varied as a result of the Scheme. In addition, the responsibilities of individual Old Summit Directors will remain unchanged in all material respects following implementation of the Scheme.

On the Scheme Effective Date, assuming that no further Old Summit Shares have been purchased or issued after the Latest Practicable Date, certain of the Old Summit Directors will have the following beneficial interests in New Summit Shares by virtue of the effect of the Scheme on their Old Summit Shares.

The interests of the Old Summit Directors together represent approximately 62.8 per cent. of the issued Old Summit Shares in existence as at the Latest Practicable Date.

The effect of the Scheme on the interests of Old Summit Directors in their capacity as holders of Old Summit Shares will not differ from the effect of the Scheme on the interests of other holders of Old Summit Shares.

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Your attention is drawn to the letter from the Executive Chairman and Chief Executive Officer in Part 1 of this document and to the Scheme set out in Part 4 of this document. Copies of:

are available in electronic form from Old Summit’s website at www.summitplc.com.

In the case of joint holders of Old Summit Shares, subject to compliance with applicable laws, one copy of this document is being delivered to the first registered joint holder. Further copies of this document may be requested by joint holders other than the first registered joint holder by application in writing to Link Asset Services.

You will find enclosed with this document:

IT IS IMPORTANT THAT, FOR THE COURT MEETING IN PARTICULAR, AS MANY VOTES AS POSSIBLE ARE CAST SO THAT THE COURT MAY BE SATISFIED THAT THERE IS A FAIR AND REASONABLE REPRESENTATION OF OLD SUMMIT SHAREHOLDER OPINION. YOU ARE THEREFORE STRONGLY ENCOURAGED TO SIGN AND RETURN YOUR FORMS OF PROXY AS SOON AS POSSIBLE.

IN LIGHT OF THE ONGOING COVID-19 PANDEMIC AND ASSOCIATED DIFFICULTIES WITH THE HOLDING OF PHYSICAL SHAREHOLDER MEETINGS, AS PERMITTED BY THE CORPORATE INSOLVENCY AND GOVERNANCE ACT 2020, THE MEETINGS WILL BE HELD BY TELEPHONE. THE COMPANY WILL BE PROVIDING A LISTEN-ONLY CONFERENCE CALL FACILITY TO ENABLE OLD SUMMIT SHAREHOLDERS TO FOLLOW PROCEEDINGS OF THE MEETINGS REMOTELY. ALL OLD SUMMIT SHAREHOLDERS ARE ENCOURAGED TO USE THIS FACILITY AND TO FOLLOW PROCEEDINGS OF THE MEETINGS IN REAL TIME IF THEY WISH TO DO SO. ANY OLD SUMMIT SHAREHOLDER WHO WISHES TO LISTEN TO THE MEETINGS BY SUCH MEANS SHOULD CONTACT THE COMPANY PRIOR TO THE DAY OF THE MEETINGS VIA EMAIL AT INVESTORS@SUMMITPLC.COM (INCLUDING THEIR INVESTOR CODE) IN ORDER TO REQUEST DIAL-IN DETAILS. OLD SUMMIT SHAREHOLDERS USING THE CONFERENCE CALL FACILITY WILL NOT BE ABLE TO VOTE OR ASK QUESTIONS USING THIS SERVICE. ACCORDINGLY, IF OLD SUMMIT SHAREHOLDERS WISH TO HAVE THEIR VOTE COUNTED AT THE MEETINGS, THEY MUST VOTE BY SUBMITTING THEIR FORMS OF PROXY OR APPOINTING THEIR PROXY ELECTRONICALLY (AS THE CASE MAY BE) BY THE RELEVANT TIME. THE MEETINGS WILL END IMMEDIATELY AFTER THE FORMAL BUSINESS. YOU ARE THEREFORE STRONGLY URGED TO RETURN YOUR FORMS OF PROXY OR APPOINT YOUR PROXY ELECTRONICALLY (AS THE CASE MAY BE), APPOINTING THE CHAIRMAN OF THE RELEVANT MEETING AS YOUR PROXY BY THE RELEVANT TIME. UNLESS THE FORMS OF PROXY ARE RETURNED BY THE RELEVANT TIME, THEY WILL BE INVALID AND YOUR VOTE WILL NOT BE COUNTED.

You are requested to complete, sign and return the Forms of Proxy as soon as possible and in any event at least 48 hours before the time fixed for the relevant Meeting (excluding any part of the day that is not a Business Day). If you hold your Old Summit Shares in uncertificated form and wish to appoint a proxy through the CREST electronic proxy appointment service, please read the notes to the notices of the Court Meeting and General Meeting in Parts 5 and 6 of this document for further details.

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Registered holders of Old Summit ADSs as at the ADS Voting Record Time will be contacted by the Depositary for the Old Summit ADSs with guidelines on how to provide voting instructions to the Depositary with respect to the Old Summit ADSs. In order to vote, holders of Old Summit ADSs are required to follow the voting instructions and to meet the deadlines provided by the Depositary. Persons that hold Old Summit ADSs in accounts with brokers or other securities intermediaries as at the ADS Voting Record Time should follow the instructions provided by their brokers or other securities intermediaries.

Multiple proxy voting instructions

As a registered Old Summit Shareholder, you are entitled to appoint a proxy in respect of some or all of your Old Summit Shares. You are also entitled to appoint more than one proxy. However, in accordance with the special arrangements for the Meetings described above, you are only permitted to appoint the chairman of the Meetings as your proxy. A space has been included on the Forms of Proxy to allow you to specify the number of Old Summit Shares in respect of which your proxy is appointed.

HELPLINE

If you have any questions relating to this document or the completion and return of the Forms of Proxy, please call Link Asset Services on 0371 664 0321. Calls are charged at the standard geographic rate and will vary by provider. Calls from outside the United Kingdom will be charged at the applicable international rate. The helpline is open between 9.00 a.m. – 5.30 p.m., Monday to Friday excluding public holidays in England and Wales. Please note that Link Asset Services cannot provide any financial, legal or tax advice and calls may be recorded and monitored for security and training purposes.

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PART 3

ADDITIONAL INFORMATION

As a company incorporated in Delaware, New Summit will be required to comply with applicable Delaware law. The applicable provisions of the Companies Act differ from laws applicable to Delaware corporations and their shareholders. Set forth below is a summary of certain differences between the provisions of the Companies Act and the Delaware General Corporation Law and between the Old Summit Articles and the New Summit Certificate of Incorporation and New Summit Bylaws relating to shareholders’ rights and protections which may impact upon the rights of Old Summit Shareholders when they become holders of New Summit Shares. This summary is not intended to be a complete discussion of the respective rights and it is qualified in its entirety by reference to English law, Delaware law, the Old Summit Articles, the New Summit Certificate of Incorporation and the New Summit Bylaws.

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This list is intended to be illustrative only and does not purport to be exhaustive or to constitute legal advice. Any Old Summit Shareholder wishing to obtain further information regarding his or her rights as a holder of New Summit Shares under Delaware law should consult his or her US legal advisers.

Following and subject to the Scheme becoming Effective, New Summit will be required to comply with any applicable requirements of the US Securities Act, the US Exchange Act and any other applicable US state or federal securities laws or pursuant to the rules of the Nasdaq Global Market.

Notwithstanding the differences between the provisions of the Companies Act and the Delaware General Corporation Law and between the Old Summit Articles and the New Summit Certificate of Incorporation and the New Summit Bylaws outlined above, with effect from the Scheme Effective Date, the voting rights relating to New Summit Shares will be substantially the same as the Old Summit Shares and the New Summit Shares will rank pari passu for dividends and in all respects with other fully paid New Summit Shares in issue on the Scheme Effective Date.

Copies of the Old Summit Articles, the New Summit Certificate of Incorporation and New Summit Bylaws are also available in electronic form on Old Summit’s website at www.summitplc.com.

On 17 July 2020, New Summit’s board of directors adopted and its shareholder approved the 2020 Stock Incentive Plan (the “2020 Plan”), which, provided the approval of the Old Summit Shareholders is also obtained, will become effective immediately on the Scheme Effective Date. New Summit is seeking approval of the 2020 Plan by the Old Summit Shareholders in an effort to ensure that the 2020 Plan satisfies the requirements of the listing rules of the Nasdaq Global Market, without the cost and delay that a separate meeting of New Summit’s stockholders following the Scheme Effective Date would incur.

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The 2020 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. Upon effectiveness of the 2020 Plan, the number of shares of New Summit’s common stock that will be reserved for issuance under the 2020 Plan will be the sum of (1) 8,000,000 shares; plus (2) the number of shares (up to a maximum of 5,000,000 shares) as is equal to the number of shares of New Summit’s common stock subject to awards granted by Old Summit prior to the Scheme Effective Date pursuant to the Old Summit Share Plans and assumed or replaced by New Summit on or following the Scheme Effective Date that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by New Summit at their original issuance price pursuant to a contractual repurchase right; plus (3) an annual increase, to be added on the first day of each fiscal year, beginning with the fiscal year ending 31 December 2021 and continuing until, and including, the fiscal year ending 31 December 2030, equal to the least of (i) 6,400,000 shares of New Summit’s common stock (ii) 4 (four) per cent. of the number of shares of New Summit’s common stock outstanding on such date, and (iii) an amount determined by New Summit’s board of directors. Any or all of the shares of common stock available for issuance under the 2020 Plan may be issued as incentive stock options.

Employees, officers, directors, consultants and advisers of New Summit and of New Summit’s present or future parent or subsidiary corporations (and any other business venture in which New Summit has a controlling interest, as determined by the New Summit board of directors) are eligible to receive awards under the 2020 Plan; however, only employees eligible to receive incentive stock options under Section 422 of the US Internal Revenue Code, as amended (the “Code”) may be granted incentive stock options.

Pursuant to the terms of the 2020 Plan, New Summit’s board of directors (or a committee delegated by New Summit’s board of directors) will administer the 2020 Plan and, subject to any limitations set forth in the 2020 Plan, will select the recipients of awards and determine:

If New Summit’s board of directors delegates authority to one or more of New Summit’s officers to grant awards under the 2020 Plan, the officer will have the power to make awards to employees, except officers and executive officers (as such terms are defined in the 2020 Plan). New Summit’s board of directors will fix the terms of the awards to be granted by any such officer, the maximum number of shares subject to awards that any such officer may grant, and the time period in which such awards may be granted.

Effect of certain changes in capitalisation

In the event of any stock split, reverse stock split, stock dividend, recapitalisation, combination of shares, reclassification of shares, spin-off or other similar change in capitalisation or event, or any dividend or distribution to holders of New Summit’s common stock other than an ordinary cash dividend, New Summit is required by the 2020 Plan to make equitable adjustments (or make substitute awards, if applicable), in the manner determined by New Summit’s board of directors, to:

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Effect of certain corporate transactions

Upon the occurrence of a merger or other reorganisation event (as defined in the 2020 Plan), New Summit’s board of directors may, on such terms as New Summit’s board of directors determines (except to the extent specifically provided otherwise in an applicable award agreement or other agreement between the participant and New Summit), take any one or more of the following actions pursuant to the 2020 Plan as to all or any (or any portion of) outstanding awards, other than awards of restricted stock:

In taking any of the foregoing actions, New Summit’s board of directors is not obligated by the 2020 Plan to treat all awards, all awards held by a participant, or all awards of the same type, identically.

In the case of certain restricted stock units, no assumption or substitution is permitted, and the restricted stock units will instead be settled in accordance with the terms of the applicable restricted stock unit agreement.

Upon the occurrence of a reorganisation event other than New Summit’s liquidation or dissolution, New Summit’s repurchase and other rights with respect to each outstanding award of restricted stock will continue for the benefit of the succeeding company and will, unless New Summit’s board of directors determines otherwise, apply to the cash, securities, or other property which New Summit’s common stock is converted into or exchanged for pursuant to the reorganisation event in the same manner and to the same extent as they applied to the common stock subject to the restricted stock award. However, New Summit’s board of directors may provide for the termination or deemed satisfaction of such repurchase or other rights under the restricted stock award agreement or in any other agreement between a participant and New Summit, either initially or by amendment. Upon the occurrence of a reorganisation event involving New Summit’s liquidation or dissolution, except to the

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extent specifically provided to the contrary in the restricted stock award agreement or any other agreement between the participant and New Summit, all restrictions and conditions on each outstanding restricted stock award will automatically be deemed terminated or satisfied.

New Summit’s board of directors may, at any time, provide that any award under the 2020 Plan will become immediately exercisable in whole or in part, free of some or all restrictions or conditions, or otherwise realisable in whole or in part, as the case may be.

Except with respect to certain actions requiring stockholder approval under the Code, or Nasdaq Stock Market rules, New Summit’s board of directors may amend, modify or terminate any outstanding award under the 2020 Plan, including but not limited to, substituting for the award another award of the same or a different type, changing the date of exercise or realisation, and converting an incentive stock option to a non-statutory stock option, subject to certain participant consent requirements. However, unless New Summit’s stockholders approve such action, the 2020 Plan provides that New Summit may not (except as otherwise permitted in connection with a change in capitalisation or reorganisation event):

No award may be granted under the 2020 Plan on or after the date that is ten years from the effectiveness of the 2020 Plan. New Summit’s board of directors may amend, suspend or terminate the 2020 Plan at any time, except that stockholder approval may be required to comply with applicable law or stock market requirements.

On 17 July 2020, New Summit’s board of directors adopted and its shareholder approved the 2020 Employee Stock Purchase Plan (the “2020 ESPP”), which, provided the approval of the Old Summit Shareholders is also obtained, will become effective on the Scheme Effective Date. New Summit is seeking approval of the 2020 ESPP by the Old Summit Shareholders in an effort to ensure that the 2020 ESPP satisfies the requirements of the listing rules of the Nasdaq Global Market, without the cost and delay that a separate meeting of New Summit’s stockholders following the Scheme Effective Date would incur.

The 2020 ESPP will be administered by New Summit’s board of directors or by a committee appointed by New Summit’s board of directors. The 2020 ESPP initially provides participating employees with the opportunity to purchase up to an aggregate of 1,000,000 shares of New Summit’s common stock. The number of shares of New Summit’s common stock reserved for issuance under the 2020 ESPP will automatically increase on the first day of each fiscal year, beginning with the fiscal year commencing on 1 January 2021 and continuing for each fiscal year until, and including the fiscal year commencing on, 1 January 2030, in an amount equal to the lowest of (1) 1,600,000 shares of New Summit’s common stock, (2) 1 (one) per cent. of the number of shares of New Summit’s common stock outstanding on such date, and (3) an amount determined by New Summit’s board of directors.

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All of New Summit’s employees and employees of any designated subsidiary, as defined in the 2020 ESPP, are eligible to participate in the 2020 ESPP, provided that:

New Summit retains the discretion to determine which eligible employees may participate in an offering under applicable regulations.

New Summit expects to make one or more offerings to eligible employees to purchase stock under the 2020 ESPP beginning at such time and on such dates as New Summit’s board of directors may determine, or on the first business day thereafter. Each offering will consist of a six-month offering period during which payroll deductions will be made and held for the purchase of New Summit’s common stock at the end of the offering period. New Summit’s board of directors or a committee designated by the board of directors may, at its discretion, choose a different period of not more than 12 months for offerings.

On each offering commencement date, each participant will be granted an option to purchase, on the last business day of the offering period, up to a number of shares of New Summit’s common stock determined by multiplying US$2,083 by the number of full months in the offering period and dividing that product by the closing price of New Summit’s common stock on the first day of the offering period. No employee may be granted an option under the 2020 ESPP that permits the employee’s rights to purchase shares under the 2020 ESPP and any other employee stock purchase plan of New Summit’s or of any of New Summit’s subsidiaries to accrue at a rate that exceeds US$25,000 of the fair market value of New Summit’s common stock (determined as of the first day of each offering period) for each calendar year in which the option is outstanding. In addition, no employee may purchase shares of New Summit’s common stock under the 2020 ESPP that would result in the employee owning 5 per cent. or more of the total combined voting power or value of New Summit’s stock or the stock of any of New Summit’s subsidiaries.

Each eligible employee may authorise up to a maximum of 15 per cent. of his or her compensation to be deducted by New Summit during the offering period. Each employee who continues to be a participant in the 2020 ESPP on the last business day of the offering period will be deemed to have exercised an option to purchase from New Summit the number of whole shares of New Summit’s common stock that his or her accumulated payroll deductions on such date will pay for, not in excess of the maximum numbers set forth above. Under the terms of the 2020 ESPP, the purchase price will be determined by New Summit’s board of directors or the committee for each offering period and will be at least 85 per cent. of the applicable closing price of New Summit’s common stock. If New Summit’s board of directors or the committee does not make a determination of the purchase price, the purchase price will be 85 per cent. of the lesser of the closing price of New Summit’s common stock on the first business day of the offering period or on the last business day of the offering period.

An employee may at any time prior to the close of business on the fifteenth business day (or such other number of days as is determined by New Summit) prior to the end of the offering period, and for any reason, permanently withdraw from participating in the offering and permanently withdraw the balance accumulated in the employee’s account. Partial withdrawals are not permitted. If an employee elects to discontinue his or her payroll deductions during an offering period but does not elect to withdraw his or her funds, funds previously deducted will be applied to the purchase of common stock at the end of the offering period. If a participating employee’s employment ends before the last business day of an offering period, no additional payroll deductions will be taken and the balance in the employee’s account will be paid to the employee.

New Summit will be required to make equitable adjustments to the extent determined by New Summit’s board of directors or a committee thereof to the number and class of securities available under the 2020 ESPP, the share limitations under the 2020 ESPP, and the purchase price for an offering period

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under the 2020 ESPP to reflect stock splits, reverse stock splits, stock dividends, recapitalisations, combinations of shares, reclassifications of shares, spin-offs and other similar changes in capitalisation or events or any dividends or distributions to holders of New Summit’s common stock other than ordinary cash dividends.

In connection with a merger or other reorganisation event, as defined in the 2020 ESPP, New Summit’s board of directors or a committee of New Summit’s board of directors may take any one or more of the following actions as to outstanding options to purchase shares of New Summit’s common stock under the 2020 ESPP on such terms as New Summit’s board of directors or committee thereof determines:

New Summit’s board of directors may at any time, and from time to time, amend or suspend the 2020 ESPP or any portion of the 2020 ESPP. New Summit will obtain stockholder approval for any amendment if such approval is required by Section 423 of the Code. Further, New Summit’s board of directors may not make any amendment that would cause the 2020 ESPP to fail to comply with Section 423 of the Code. The 2020 ESPP may be terminated at any time by New Summit’s board of directors. Upon termination, New Summit will refund all amounts in the accounts of participating employees.

The directors of New Summit intend to conduct New Summit’s affairs such that, based on current law and practice of the relevant tax authorities, New Summit will not become resident for tax purposes in any other territory other than the United States. It is assumed that New Summit does not become resident in a territory other than the United States.

The following general discussion sets forth the anticipated material United States federal income tax consequences of the Scheme to holders of Old Summit Shares or Old Summit ADSs that exchange their Old Summit Shares or Old Summit ADSs for New Summit Shares. This discussion does not address any tax consequences arising under the laws of any state, local or foreign jurisdiction, or under any United States federal laws other than those pertaining to income tax. This discussion is based

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upon the Code, the regulations promulgated under the Code and court and administrative rulings and decisions, all as in effect on the date of this discussion. These laws may change, possibly retroactively, and any change could affect the accuracy of the statements and conclusions set forth in this discussion.

This discussion addresses only those Old Summit Shareholders who, at the Scheme Record Time, are “US Holders” (as defined below) holding their Old Summit Shares or Old Summit ADSs as capital assets within the meaning of Section 1221 of the Code (generally, property held for investment). Further, this discussion does not address all aspects of United States federal income taxation that may be relevant to you in light of your particular circumstances or that may be applicable to you if you are subject to special treatment under the United States federal income tax laws, including if you are:

In addition, the discussion does not address any alternative minimum tax or any state, local or foreign tax consequences of the Scheme, nor does it address any tax consequences arising under the unearned income Medicare contribution tax pursuant to the Health Care and Education Reconciliation Act of 2010. Determining the actual tax consequences of the Scheme to you may be complex. They will depend on your specific situation and on factors that are not within the control of Old Summit or New Summit. You should consult with your own tax adviser as to the tax consequences of the Scheme in your particular circumstances.

For purposes of this discussion, the term “US Holder” means a beneficial owner of Old Summit Shares or Old Summit ADSs that is for United States federal income tax purposes (i) an individual citizen or resident of the United States, (ii) a corporation, or entity treated as a corporation, organised in or under the laws of the United States or any state thereof or the District of Columbia, (iii) a trust if (a) a court within the United States is able to exercise primary supervision over the administration of the trust and one or more United States persons have the authority to control all substantial decisions of the trust or (b) such trust has made a valid election to be treated as a US person for United States federal income tax purposes or (iv) an estate, the income of which is includible in gross income for United States federal income tax purposes regardless of its source.

The United States federal income tax consequences to a partner in an entity or arrangement that is treated as a partnership for United States federal income tax purposes and that holds Old Summit Shares or Old Summit ADSs generally will depend on the status of the partner and the activities of the partnership. Partners in a partnership holding Old Summit Shares or Old Summit ADSs should consult their own tax advisers.

Tax Consequences of the Scheme Generally

Although there is no US federal income tax authority directly addressing the tax consequences of the Scheme and the matters described below are not free from doubt, the following summary describes the principal US federal income tax consequences expected to apply to US Holders who participate

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in the Scheme. The parties intend for the Scheme to qualify as a “reorganization” within the meaning of Section 368(a) of the Code. It is a condition to the obligations of Old Summit and New Summit to complete the Scheme that each of Old Summit and New Summit receive an opinion dated the Scheme Record Time, to the effect that the Scheme will qualify as a “reorganization” within the meaning of Section 368(a) of the Code. These opinions will be based on representation letters provided by Old Summit and New Summit and on customary factual assumptions. Neither of the opinions described above will be binding on the Internal Revenue Service. Old Summit and New Summit have not sought and will not seek any ruling from the Internal Revenue Service regarding any matters relating to the Scheme and as a result, there can be no assurance that the Internal Revenue Service will not assert, or that a court would not sustain, a position contrary to any of the conclusions set forth below.

Provided the Scheme qualifies as a “reorganization” within the meaning of Section 368(a) of the Code, the expected US federal income tax consequences of the Scheme to holders or Old Summit Shares or Old Summit ADSs are as follows:

Gain or loss that Old Summit Shareholders recognise in connection with the Scheme will generally constitute capital gain or loss and will constitute long-term capital gain or loss if such holders have held their Old Summit ADSs for more than one year as of the Scheme Record Time. Long-term capital gain of certain non-corporate Old Summit Shareholders, including individuals, is generally taxed at preferential rates. The deductibility of capital losses is subject to limitations. In some cases, if a holder actually or constructively owns New Summit Shares other than New Summit Shares received pursuant to the Scheme, the recognised gain could be treated as having the effect of a distribution of a dividend under the tests set forth in Section 302 of the Code, in which case such gain would be treated as dividend income. Because the possibility of dividend treatment depends upon each holder’s particular circumstances, including the application of constructive ownership rules, New Summit Shareholders should consult their tax advisers regarding the application of the foregoing rules to their particular circumstances.

Effects on Certain US Shareholders

The Scheme should qualify as a “reorganization” within the meaning of Section 368(a)(1)(F) of the Code. In such case, subject to the potential application of the PFIC rules, the tax treatment of a US Holder in connection with the Scheme should be as follows:

US Holders that own Old Summit ADSs with a fair market value of less than US$50,000 at the Scheme Record Time should not recognise gain or loss for US federal income tax purposes as a result of the Scheme.

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A US Holder that owns Old Summit ADSs with a fair market value of US$50,000 or more (but who is not a “10 per cent. US Holder,” as defined below) at the Scheme Record Time should, unless such holder validly makes the “all earnings and profits” election described below, recognise gain, but not loss, with respect to the US Holder’s Old Summit ADSs deemed exchanged for New Summit Shares. In lieu of recognising such taxable gain, a US Holder that validly makes the “all earnings and profits” election will be required to include in income, as a deemed dividend, the “all earnings and profits amount” (as defined under applicable Treasury Regulations) that is attributable, under US tax principles, to such US Holder’s Old Summit ADSs. In general, the “all earnings and profits amount” attributable to Old Summit ADSs held by a US Holder should depend on our accumulated earnings and profits (as determined under US federal income tax principles) from the date that the Old Summit ADSs (or, if earlier, the Old Summit Shares represented thereby) were acquired by such US Holder through the Scheme Record Time. A US Holder that wishes to make an “all earnings and profits” election must comply with strict conditions for making this election under applicable Treasury Regulations.

A 10 per cent. US Holder (defined below) is subject to special rules that will generally require such 10 per cent. US Holder to include in income, as a deemed dividend, the “all earnings and profits amount” attributable to the Old Summit ADSs owned by such US Holder at the Scheme Record Time.

We are currently in the process of determining our historical earnings and profits and also expect to determine our earnings and profits for the portion of 2020 ending with the Scheme Record Time. We may not complete this determination until after completion of the Scheme. The determination of our earnings and profits is a complex determination and may be impacted by numerous factors. Accordingly, there can be no assurance that the Internal Revenue Service will agree with our determination of such earnings and profits. If the Internal Revenue Service does not agree with our determination, our actual earnings and profits may differ from the amount shown on our initial determination, which could adversely affect the US tax position of a US Holder choosing or required to include the all earnings and profits amount in the US Holder’s taxable income.

The PFIC rules

If we have been a PFIC for any taxable year during which a US Holder has held Old Summit ADSs, certain adverse tax consequences could apply to such US Holder in connection with the transactions described above.

Backup Withholding

Payments of cash to a non-corporate holder of Old Summit ADSs in connection with the Scheme may be subject to information reporting and backup withholding (currently at a rate of 24 per cent.). Such a holder generally will not be subject to backup withholding, however, if the holder:

any amounts withheld under the backup withholding rules are not additional tax and will generally be allowed as a refund or credit against the holder’s United States federal income tax liability, provided the required information is timely furnished to the Internal Revenue Service.

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This summary of certain material United States federal income tax consequences is for general information only and is not tax advice. You are urged to consult your tax adviser with respect to the application of United States federal income tax laws to your particular situation as well as any tax consequences arising under the United States federal estate or gift tax rules, or under the laws of any state, local, foreign or other taxing jurisdiction.

The following paragraphs, which are intended as a general guide only and not a substitute for detailed tax advice, are based on current legislation and on what is understood to be current HM Revenue and Customs practice. They summarise certain aspects of the UK taxation consequences of the Scheme and the holding and future disposal of New Summit Shares. Unless otherwise expressly stated, they apply only to Old Summit Shareholders (or New Summit Shareholders) who are resident in the United Kingdom for taxation purposes, who hold their Old Summit Shares (and who will hold their New Summit Shares) as an investment (other than under an individual savings account (“ISA”) or a Self-Invested Personal Pension (“SIPP”)), who are the absolute beneficial owners of those shares and who have not (and are not deemed to have) acquired those shares by virtue of an office or employment (whether current, historic or prospective). In addition, these comments may not apply to certain classes of holders of Old Summit Shares or New Summit Shares such as collective investment schemes and insurance companies.

This section does not constitute tax advice or purport to be a comprehensive analysis of all the potential tax consequences. Old Summit Shareholders who are in any doubt as to their tax position in relation to the Proposals or the holding or future disposal of New Summit Shares, or who are subject to tax in a jurisdiction other than the UK, should seek independent professional advice as to the potential tax consequences for them under the laws of their country and/or state of citizenship, domicile or residence.

The following paragraphs have been prepared on the basis that New Summit will be resident in the United States, and not resident in the United Kingdom, for tax purposes. References below to a person being UK resident are to the person being UK resident for tax purposes.

UK taxation consequences of the Scheme

Distribution

The implementation of the Scheme should not be treated as involving a distribution subject to UK tax as income.

Taxation of chargeable gains

On implementation of the Scheme, for the purposes of UK taxation of chargeable gains:

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If conditions (i) and (ii) are not met, then such an Old Summit Shareholder will be treated, on receiving New Summit Shares as consideration for the cancellation of his Old Summit Shares, as having made a disposal of the Old Summit Shares. This may, depending on individual circumstances, give rise to a chargeable gain or allowable loss.

Application may be made to HM Revenue and Customs under section 138 of the Taxation of Chargeable Gains Act 1992 for advance clearance that they accept that these conditions will be met. Such an application has been made and clearance has been granted.

Disposal of Old Summit Shares

The following would apply to Old Summit Shareholders that, as a result of the implementation of the Scheme, are (under the rules in (b) above) treated as disposing of their Old Summit Shares.

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UK taxation consequences of disposing of New Summit Shares

A subsequent disposal of New Summit Shares by a New Summit Shareholder may, depending on his individual circumstances, give rise to a chargeable gain or allowable loss for the purposes of UK taxation of chargeable gains. The rules in relation to disposals of Old Summit Shares described above (in the section entitled “UK taxation consequences of the Scheme”) will apply similarly.

On the basis that implementation of the Scheme did not give rise to a disposal of the New Summit Shareholder’s Old Summit Shares, such that any gain (or loss) was “rolled over” into the New Summit Shares (as described above), any chargeable gain or allowable loss on the disposal of New Summit Shares should be calculated taking into account the allowable original cost to the Old Summit Shareholder of acquiring the Old Summit Shares from which the New Summit Shares are derived.

On the basis that the New Summit Shares (being shares in a company that is not incorporated in the UK) will be non UK sited assets, a New Summit Shareholder that is an individual who is resident but not domiciled in the UK may, provided all relevant claims are made and charges paid, be liable to UK capital gains tax but only to the extent that chargeable gains (including rolled over gain) made on the disposal of New Summit Shares are remitted or deemed to be remitted to the UK.

Taxation of dividends

The following sets out certain UK tax implications of the payment by New Summit of cash dividends to various categories of shareholder.

UK resident and domiciled individual New Summit Shareholders

The tax treatment of dividends paid to New Summit Shareholders who are individuals and UK resident and domiciled is (except to the extent that such dividends are earned through an ISA, a SIPP or other regime which exempts the dividends from tax) as follows:

Where such a New Summit Shareholder’s dividend income for a tax year exceeds the Nil Rate Amount, the excess amount (the “Relevant Dividend Income”) will be subject to income tax at the following rates for the tax year 6 April 2020 to 5 April 2021:

In determining whether and, if so, to what extent the Relevant Dividend Income falls above or below the threshold for the higher rate of income tax or, as the case may be, the additional rate of income tax, the New Summit Shareholder’s total dividend income for the tax year in question (including the part within the Nil Rate Amount) will, as noted above, be treated as the highest part of his or her total income for income tax purposes.

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Such an individual New Summit Shareholder will be taxable on the total of the dividend before deduction of any amount deducted in respect of United States dividend withholding tax (the “gross dividend”).

UK resident but non-UK domiciled individual New Summit Shareholders

If the relevant individual New Summit Shareholder is eligible to receive and is claiming the remittance basis of taxation and remits a dividend paid on the New Summit Shares, the individual will be subject to UK income tax at a rate of 20 per cent. on the gross dividend, unless and except to the extent that the gross dividend falls above the threshold for the higher rate of income tax, in which case the individual will, to that extent, pay UK income tax at a rate of 40 per cent., unless and except to the extent that the gross dividend falls above the threshold for the additional rate of income tax, in which case the individual will, to that extent, pay UK income at a rate of 45 per cent., in each case less any amount which has been deducted in respect of United States dividend withholding tax.

Corporate New Summit Shareholders

The taxation of dividends received by New Summit Shareholders that are companies within the charge to UK corporation tax depends upon whether or not they are “small companies” for the purposes of Part 9A of the Corporation Tax Act 2009 (the UK legislation that applies to the taxation of dividends received by companies). A company will be within the charge to UK corporation tax in respect of dividends paid by New Summit if the company is either UK resident or non-UK resident but carrying on a trade in the UK through a branch, agency or permanent establishment and the New Summit Shares are attributable to such branch, agency or permanent establishment. Companies within the charge to UK corporation tax are referred to below as “UK companies”.

A UK company that is a “small company” and is in receipt of a dividend from New Summit will not generally be subject to corporation tax on the dividend provided certain conditions are met, including an anti-avoidance condition.

A UK company that is not a “small company” and is in receipt of a dividend from New Summit will not generally be subject to corporation tax on the dividend provided the dividend falls within an exempt class in Part 9A of the Corporation Tax Act 2009 and certain conditions are met, including an anti-avoidance condition. Examples of exempt classes (as defined in Chapter 3 of Part 9A of the Corporation Tax Act 2009) include dividends paid on shares that are “ordinary shares” (that is shares that do not carry any present or future preferential rights to dividends or to the Company’s assets on its winding up) and are not “redeemable” (as defined for the purpose of the Corporation Tax Act 2009) and dividends paid to a person holding less than 10 per cent. of the issued share capital of the payer (or any class of that share capital in respect of which such dividends are paid). However, the exemptions are not comprehensive and are subject to anti-avoidance rules. A UK company receiving a dividend which does not fall within an exempt class will be liable to UK corporation tax in respect of the dividend (currently, for the financial year 1 January 2020 to 31 December 2020, at a rate of 19 per cent.).

Other New Summit Shareholders

New Summit Shareholders that are UK resident but exempt from UK tax on dividends, including exempt pension funds and charities, will not be entitled to any tax credit in respect of dividends paid by New Summit.

Transfer of assets abroad: anti-avoidance legislation

The attention of individuals resident in the UK is drawn to Chapter 2 of Part 13 of the Income Tax Act 2007 (“ITA 2007”), which may render such individuals liable to income tax in respect of undistributed income or profits of New Summit. These provisions apply where a UK resident person makes a “relevant transfer” to a non-resident person and as a result income from which the individual may benefit becomes payable to that non-resident person.

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However, the provisions do not apply if one of several exemptions apply. An exemption (under section 742A ITA 2007) applies if conditions (a) to (c) below are met, namely:

New Summit Shareholders are advised to take independent advice on the potential application of Chapter 2 of Part 13 of the ITA 2007 in the light of their own circumstances.

Attribution of gains to members of non-UK resident close companies

The attention of UK resident persons (whether or not domiciled in the UK) is drawn to the provisions of section 3 of the Taxation of Chargeable Gains Act 1992. Under these provisions, if a non-UK resident company (such as New Summit) is controlled by five or fewer persons, or by its directors, then, if certain conditions are satisfied, the capital gains of the company may be apportioned and taxed in the hands of any UK resident participator in the company if and to the extent that his indirect share of the gain (including the share of any person connected with him) exceeds 25 per cent. These rules only apply if the gain is connected to avoidance of capital gains tax or corporation tax. The rules apply to non-domiciled persons in a modified way.

Stamp Duty and Stamp Duty Reserve Tax

No stamp duty or stamp duty reserve tax (“SDRT”) will be payable on the cancellation of the Old Summit Shares or the allotment and the issue of New Summit Shares pursuant to the Scheme.

The conveyance or transfer on sale of shares is generally subject to ad valorem stamp duty, normally at a rate of 0.5 per cent. (rounded up to the nearest £5) of the amount or value of the consideration. No duty is payable on transactions, the total value of which is less than £1,000.

UK stamp duty will in principle be payable on any instrument of transfer of the New Summit Shares which is executed in the UK or which “relates to any matter or thing done or to be done” in the UK. However, in practice, UK stamp duty should generally not need to be paid on any instruments transferring New Summit Shares, provided that such transfer instruments are executed and retained outside of the UK. No UK SDRT will be payable in respect of any agreement to transfer New Summit Shares. These statements have been prepared on the basis that the New Summit Shares are not registered in a register kept in the UK by or on behalf of New Summit. It is not intended that such a register will be kept in the UK. The New Summit Shares will be registered in a register kept in Delaware.

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PART 4

SCHEME OF ARRANGEMENT

(under Part 26 of the Companies Act 2006)

IN THE MATTER OF SUMMIT THERAPEUTICS PLC

and

IN THE MATTER OF THE COMPANIES ACT 2006

SCHEME OF ARRANGEMENT

(under Part 26 of the Companies Act 2006)

between

SUMMIT THERAPEUTICS PLC

and

THE HOLDERS OF THE SCHEME SHARES

(as hereinafter defined)

PRELIMINARY

Preliminary

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The Scheme

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With effect from and including the Scheme Effective Date:

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Each instruction in force at the Scheme Effective Date as to notices and other communications and other instructions from Old Summit shall, unless and until varied or revoked, be deemed from and including the Scheme Effective Date to be a valid and effective mandate or instruction to New Summit in relation to the corresponding New Summit Shares to be allotted and issued pursuant to the Scheme. However, the Old Summit ADS facility will not be replicated by New Summit.

The Scheme shall become Effective as soon as a copy of the order of the Court sanctioning the Scheme under section 899 of the Companies Act and confirming the Old Summit Reduction of Capital under the Scheme pursuant to section 648 of the Companies Act, together with the Statement of Capital, have been duly delivered to the Registrar of Companies for registration.

Old Summit and New Summit may jointly consent on behalf of all persons concerned to any modification of or addition to the Scheme or to any condition which the Court may think fit to approve or impose.

Old Summit is authorised and permitted to pay all the costs and expenses relating to the negotiation, preparation and implementation of the Scheme.

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Dated: 27 July 2020

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PART 5

NOTICE OF COURT MEETING

BUSINESS AND PROPERTY COURTS OF ENGLAND AND WALES

COMPANIES COURT (ChD)

Insolvency and Companies Court Judge Barber

IN THE MATTER OF SUMMIT THERAPEUTICS PLC

and

IN THE MATTER OF THE COMPANIES ACT 2006

NOTICE IS HEREBY GIVEN that by an Order dated 24 July 2020 made in the above matters, the Court has given permission for Summit Therapeutics plc (the “Company”) to convene a meeting (the “Court Meeting”) of the holders of the Scheme Shares (as defined in the Scheme referred to below), for the purpose of considering and, if thought fit, approving (with or without modification) a Scheme of Arrangement pursuant to section 899 of the Companies Act 2006 proposed to be made between the Company and the holders of the Scheme Shares and that such meeting will be held on 19 August 2020 at 1.30 p.m. (London time). The Court Meeting will be held in accordance with the provisions of the Corporate Insolvency and Governance Act 2020.

A copy of the said Scheme of Arrangement and a copy of the explanatory statement required to be furnished pursuant to section 897 of the Companies Act 2006 are incorporated in the document of which this notice forms part.

At the Court Meeting, the following resolution will be proposed:

“That the Scheme between the Company and the Scheme Shareholders, a print of which has been produced to this meeting and for the purposes of identification signed by the chairman hereof, in its original form or as amended in accordance with its terms or with or subject to any modification, addition or condition approved or imposed by the Court and agreed by the Company and Summit Therapeutics Inc. be approved.”

Holders of Scheme Shares are not entitled to attend or otherwise participate in the Court Meeting but are entitled to vote at the Court Meeting by proxy. For these purposes, holders of Scheme Shares may appoint the Chairman of the Court Meeting as their proxy to attend and vote in their stead. A BLUE Form of Proxy for use at the Court Meeting is enclosed herewith.

In order to appoint the Chairman of the Court Meeting as proxy, the BLUE Form of Proxy (together with any power of attorney or other authority under which it is signed, or a notarially certified copy of such authority) must be lodged with the Company’s registrar, Link Asset Services, in accordance with the instructions printed thereon not later than 48 hours (excluding any part of the day that is not a Business Day) before the start of the meeting.

Registered holders of Old Summit ADSs as at the ADS Voting Record Time will be contacted by The Bank of New York Mellon as depositary for the Old Summit ADSs (the “Depositary”) with guidelines on how to provide voting instructions to the Depositary with respect to the Old Summit ADSs. In order to vote, holders of Old Summit ADSs are required to follow the voting instructions and to meet the deadlines provided by the Depositary. Persons that hold Old Summit ADSs in accounts with brokers or other securities intermediaries as at the ADS Voting Record Time should follow the instructions provided by their brokers or other securities intermediaries.

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Entitlement to attend and vote at the Court Meeting, or any adjournment thereof, and the number of votes which may be cast thereat will be determined by reference to the register of members of the Company at 1.30 p.m. on the day which is two days before the date of the Court Meeting or adjourned meeting (as the case may be) (excluding any part of the day that is not a Business Day). In each case, changes to the register of members of the Company after such time will be disregarded in determining the rights of any person to attend or vote at the meeting, or at any adjournment thereof.

Voting at the Court Meeting will be conducted on a poll rather than a show of hands. By the said Order, the Court has appointed Ventzislav Stefanov (a director of the Company) or, failing him, Murdo Guy (a senior employee of the Company or, failing them, any other director of the Company to act as Chairman of the Court Meeting and has directed the Chairman to report the result of the Court Meeting to the Court.

The said Scheme of Arrangement will be subject to the subsequent sanction of the

Court. Dated 27 July 2020

CMS Cameron McKenna

Nabarro Olswang LLP

Cannon Place 78

Cannon Street London

EC4N 6AF

Solicitors for Summit Therapeutics plc

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Notes:

Special arrangements for the Court Meeting

In light of the ongoing COVID-19 pandemic and associated difficulties with the holding of physical shareholder meetings, as permitted by the Corporate Insolvency and Governance Act 2020, the Court Meeting will be held by telephone. The Company will be providing a listen-only conference call facility to enable Old Summit Shareholders to follow proceedings of the Court Meeting remotely. All Old Summit Shareholders are encouraged to use this facility and to follow proceedings of the Court Meeting in real time if they wish to do so. Any Old Summit Shareholder who wishes to listen to the Court Meeting by such means should contact the Company prior to the day of the Court Meeting via email at investors@summitplc.com (including their Investor Code) in order to request dial-in details. Old Summit Shareholders using the conference call facility will not be able to vote or ask questions using this service. Accordingly, if Old Summit Shareholders wish to have their vote counted at the Court Meeting, they must vote by submitting their BLUE Form of Proxy or appointing their proxy electronically (as the case may be) by the relevant time. The Court Meeting will end immediately after the formal business. You are therefore strongly urged to return your BLUE Form of Proxy or appoint your proxy electronically (as the case may be), appointing the chairman of the Court Meeting as your proxy by the relevant time. Unless the BLUE Form of Proxy is returned by the relevant time, it will be invalid and your vote will not be counted.

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PART 6

NOTICE OF GENERAL MEETING

SUMMIT THERAPEUTICS PLC

(registered in England and Wales with No. 05197494)

NOTICE IS HEREBY GIVEN that a General Meeting of Summit Therapeutics plc (the “Company”) will be held on 19 August 2020 at 1.40 p.m. (or as soon as possible after the meeting of the holders of ordinary shares of one pence each in the capital of the Company convened by the High Court of Justice in England and Wales for the same place and date has been concluded or adjourned) for the purpose of considering and, if thought fit, passing the following resolutions:

RESOLUTION 1

AS A SPECIAL RESOLUTION

THAT for the purpose of giving effect to the scheme of arrangement dated 27 July 2020 between the Company and the Scheme Shareholders (each as defined in the said scheme), a print of which has been produced to this meeting and for the purposes of identification signed by the chairman hereof, in its original form or as amended in accordance with its terms or with or subject to any modification, addition or condition approved or imposed by the Court and agreed by the Company and Summit Therapeutics Inc. (“New Summit”) (the “Scheme”):

“165. Scheme of Arrangement

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RESOLUTION 2

AS AN ORDINARY RESOLUTION

THAT the Summit Therapeutics Inc. 2020 Stock Incentive Plan, a copy of the rules for which is now produced to this meeting and initialled by the Chairman for the purposes of identification, be and is hereby approved.

RESOLUTION 3

AS AN ORDINARY RESOLUTION

THAT the Summit Therapeutics Inc. 2020 Employee Stock Purchase Plan, a copy of the rules for which is now produced to this meeting and initialled by the Chairman for the purposes of identification, be and is hereby approved.

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Notes:

Special arrangements for the General Meeting

In light of the ongoing COVID-19 pandemic and associated difficulties with the holding of physical shareholder meetings, as permitted by the Corporate Insolvency and Governance Act 2020, the General Meeting will be held by telephone. The Company will be providing a listen-only conference call facility to enable Old Summit Shareholders to follow proceedings of the General Meeting remotely. All Old Summit Shareholders are encouraged to use this facility and to follow proceedings of the General Meeting in real time if they wish to do so. Any Old Summit Shareholder who wishes to listen to the General Meeting by such means should contact the Company prior to the day of the General Meeting via email at investors@summitplc.com (including their Investor Code) in order to request dial-in details. Old Summit Shareholders using the conference call facility will not be able to vote or ask questions using this service. Accordingly, if Old Summit Shareholders wish to have their vote counted at the General Meeting, they must vote by submitting their WHITE Form of Proxy or appointing their proxy electronically (as the case may be) by the relevant time. The General Meeting will end immediately after the formal business. You are therefore strongly urged to return your WHITE Form of Proxy or appoint your proxy electronically (as the case may be), appointing the chairman of the General Meeting as your proxy by the relevant time. Unless the WHITE Form of Proxy is returned by the relevant time, it will be invalid and your vote will not be counted.

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