Interim Management Statement

Antisoma Interim Management Statement

London, UK, and Cambridge, MA: May 20 2011 - Antisoma plc (LSE: ASM; USOTC: ATSMY) today publishes its Interim Management Statement for the period from 1 January to May 19 2011.

Chairman's statement

Review

In January, our phase III trial of AS1413 showed no benefit over standard therapy. Development of the drug was therefore discontinued. Following this, we announced with our interim results in February that we were seeking a transaction to maximise value for shareholders from the Company's remaining product assets and its cash resources.

The Company held cash and cash equivalents of £15.0 million as at 31 March 2011.

The Company also announced with its interim results the intention to scale back operations in order to conserve cash. Accordingly, permanent headcount has now been reduced to nil and the Board has been cut to five members. Programme costs have been reduced to a minimal level and cash outflows have therefore fallen significantly.

Outlook

The Board continues to consider options for the Company, and further announcements will be made if and when there are material developments to report.

Grahame Cook

Chairman

Enquiries:

Antisoma plc +44 203 249 2100

Grahame Cook, Chairman

This Interim Management Statement is published in accordance with the UK Listing Authority's Disclosure Rules and Transparency Rules, in respect of the period from 1 January 2011 to May 19 2011.

Except for the historical information presented, certain matters discussed in this statement are forward looking statements that are subject to a number of risks and uncertainties that could cause actual results to differ materially from results, performance or achievements expressed or implied by such statements. These risks and uncertainties may be associated with product discovery and development, including statements regarding the company's clinical development programmes, the expected timing of clinical trials and regulatory filings. Such statements are based on management's current expectations, but actual results may differ materially.