Posting of Circular

10 November 2011

NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION IN WHOLE OR IN PART IN, INTO OR FROM ANY JURISDICTION WHERE TO DO THE SAME WOULD CONSTITUTE A VIOLATION OF THE RELEVANT LAWS OF SUCH JURISDICTION.

Antisoma plc

Proposed Delisting from the Official List and Admission to AIM

Proposed Investing Policy

Proposed changes to the Board

Summary

·; The Company announces the publication today of a Circular to Shareholders incorporating a Notice of General Meeting containing resolutions proposing:

- the authorisation of the cancellation of the listing of the Ordinary Shares on the Official List;

- the application for the admission of the Ordinary Shares to trading on AIM; and

- the approval of a formal Investing Policy.

·; The Board believes that AIM rather than the Main Market, would be more appropriate for the trading of Ordinary Shares in Antisoma given the Company's current strategy and size.

·; Antisoma also announces certain changes to the Board which are expected to take effect immediately following the Annual General Meeting. These changes include:

- the retirement of Grahame Cook and Michael Lewis; and

- the proposed appointment of Ross Hollyman as an additional Non-Executive Director.

Enquiries:

Altium Capital Limited ("Altium"), which is regulated in the United Kingdom by the Financial Services Authority, is acting solely for the Company in relation to the Proposals and nobody else and will not be responsible to anyone other than the Company for providing the protections afforded to clients of Altium nor for providing advice in relation to the Proposals or any other matter referred to in this announcement or the Circular.

A copy of this announcement will be published on Antisoma's website at www.antisoma.com. For the avoidance of doubt, the contents of this website are not incorporated into and do not form part of this announcement.

Antisoma plc

Proposed Delisting from the Official List and Admission to AIM

Proposed Investing Policy

Proposed changes to the Board

1. Introduction

On 26 September 2011, Antisoma announced that the Board was considering the potential benefits of de-listing the Company's Ordinary Shares from the Official List and seeking their admission to trading on AIM. The Board has concluded that AIM would be more appropriate for the trading of Ordinary Shares in Antisoma and the Company is pleased to announce the publication today of a circular to Shareholders, incorporating the Notice of General Meeting, (the "Circular") setting out proposals, inter alia, to cancel the listing of the Ordinary Shares on the Official List and to trading on the Main Market and to seek admission to trading of the Ordinary Shares on AIM and to approve a formal Investing Policy.

Antisoma also announces certain changes to the Board which are expected to take effect from the conclusion of the Annual General Meeting, notice of which has also been published today.

All capitalised terms in this announcement have the same meaning as defined in paragraph 10 of this announcement.

2. Background to and reasons for the proposed move to AIM

Following the discontinuation of key clinical trials in early 2011, the Board took action to curtail investment in the Company's development programmes and reduce central overheads to a minimum in order to preserve cash resources. The continuing Directors have subsequently been evaluating a range of new commercial and acquisition opportunities in order to generate value for Shareholders.

The Board believes that AIM rather than the Main Market, would be more appropriate for the trading of Ordinary Shares in Antisoma given the Company's current strategy and size. It believes the Company and its Shareholders would benefit significantly from lower transactional costs and simpler administration and regulatory requirements. In particular, the Board believes that a move to AIM will mean that corporate transactions can be executed more quickly and cost effectively compared to the Official List. The Board believes that this is likely to be a significant benefit to Antisoma going forward.

The Board is, therefore, proposing to cancel the listing of the Ordinary Shares on the Official List and to trading on the Main Market and to seek admission to trading of the Ordinary Shares on AIM.

The Listing Rules require that if a company wishes to cancel its listing on the Official List then it must seek the approval of not less than 75 per cent. of its shareholders in a general meeting voting in person or by proxy. Accordingly a special resolution is being proposed at the General Meeting to authorise the Board to cancel the listing of the Ordinary Shares on the Official List and to remove such Ordinary Shares from trading on the Main Market and to apply for admission of the Ordinary Shares to trading on AIM.

Admission will not affect the way in which Shareholders buy or sell Ordinary Shares and, following the Delisting and subsequent Admission, Ordinary Shares that are held in uncertificated form will continue to be held and dealt through CREST. Share certificates representing those Ordinary Shares held in certificated form will continue to be valid and no new share certificates will be issued.

It is emphasised that the Delisting and Admission will have no impact on the assets and liabilities of the Company.

3. Investing Company status and Investing Policy

As a result of the Board's abovementioned exercise to curtail investment in the Company's development programmes and reduce central overheads to a minimum, the majority of the Company's assets are currently cash or cash equivalents. The continuing Directors have been evaluating a range of new commercial and acquisition opportunities across a range of sectors in order to invest the cash and generate value for Shareholders. Antisoma has historically been classified as a commercial company under chapter 6 of the Listing Rules and has not previously been required to adopt a formal investing policy. However, upon Admission, the Board expects the Company to be classified as an Investing Company as defined by the AIM Rules and is therefore proposing to adopt a formal Investing Policy which will comply with the requirements of the AIM Rules. The proposed Investing Policy reflects the Board's broader, more flexible approach to creating Shareholder value.

The Directors intend to identify investment opportunities offering the potential to deliver a favourable return to Shareholders over the medium term, primarily in the form of a capital gain. A particular consideration will be to identify businesses which, in the opinion of the Directors, are under-performing and present opportunities for value creation. The Company's equity interest in a potential investment may range from a minority position to 100 per cent. ownership and the interest may be either quoted or unquoted.

The Directors intend to be active investors and to assist in the strategic development and growth of significant acquisitions and/or investments made by the Company. The acquisitions or investments may be funded from existing cash resources, by the issue of new Ordinary Shares or with debt, or a combination thereof, as the Board deems appropriate.

It is anticipated that returns to Shareholders will be delivered principally through capital growth rather than capital distributions via dividends, although it may become appropriate to distribute funds to Shareholders once the Company's investments mature.

The Directors are at an early stage of screening potential opportunities but have not, at this stage, commissioned any due diligence nor entered into any firm commitment in connection with any acquisitions or investments. Initial due diligence will be carried out by the Directors who may subsequently commission third party due diligence as appropriate.

An ordinary resolution to be proposed at the General Meeting seeks Shareholder approval of the Company's Investing Policy, which is a pre-condition to Admission. The Directors will also seek Shareholder approval of the Company's Investing Policy on an annual basis in general meeting, as required by the AIM Rules.

4. General Meeting

The Notice of General Meeting, to be held at the offices of CMS Cameron McKenna LLP, Mitre House, 160 Aldersgate Street, London EC1A 4DD at 10.30 a.m. on 7 December 2011, is set out in the Circular.

A Blue Form of Proxy for use in connection with the General Meeting will be enclosed with the Circular. Whether or not Shareholders intend to attend the General Meeting in person, it is important that they duly complete, execute and return the Blue Form of Proxy, by hand or by post to the Company's registrars, Capita Registrars, PXS, 34 Beckenham Road, Beckenham, BR3 4TU.

5. Board recommendation

The Board believes that the Proposals are in the best interests of Shareholders taken as a whole and unanimously recommends that Shareholders vote in favour of the resolutions to be proposed at the General Meeting, as set out in the Notice of General Meeting contained in the Circular, as the Directors each intend to do in respect of their own beneficial holdings of Ordinary Shares which amount in total to 3,636,781 Ordinary Shares, representing approximately 0.57 per cent. of the issued ordinary share capital of the Company.

6. Irrevocable undertakings in relation to the Proposals

ORA Capital Partners Limited and Leventis Holding SA, have irrevocably undertaken to vote in favour of the resolutions to be proposed at the General Meeting with respect to an aggregate of 174,174,744 and 44,402,831 Ordinary Shares respectively, representing, in aggregate, 34.19 per cent. of the issued ordinary share capital of the Company.

7. Expected timetable of principal events

8. Proposed Board changes

As a result of the Delisting and Admission, and the Company's expected classification as an Investing Company, changes to the Board are to be made. Michael Lewis and Grahame Cook will not be seeking re-appointment at the Annual General Meeting and will retire from the Board at the conclusion of the Annual General Meeting. It is proposed that Michael Pappas will, subject to his re-appointment at the Annual General Meeting, succeed Grahame Cook as Non-Executive Chairman.

In addition, it is proposed that Ross Hollyman be appointed as an additional Non-Executive Director at the Annual General Meeting. Mr. Hollyman has been employed in the investment industry in the UK for over 17 years. He has previously been an investment director at GAM Limited and JP Morgan Fleming Asset Management and most recently was Head of Global Equities at Liontrust Asset Management plc.

9. General

The Circular (containing a Notice of General Meeting) and the Blue Form of Proxy, the notice of Annual General Meeting and the White Form of Proxy have all been posted to Shareholders and will shortly be made available on the Company's website at www.antisoma.com. The Circular, Blue Form of Proxy, notice of Annual General Meeting and White Form of Proxy have also been submitted to the National Storage Mechanism and will shortly be available for inspection at www.hemscott.com/nsm.do

10. Definitions

The following definitions apply throughout this announcement, unless the context otherwise requires: