Disposal of AS1411

Antisoma plc

Antisoma announces asset purchase agreement with Advanced Cancer Therapeutics Inc for cancer drug AS1411

London, UK: 28 April 2011 - Antisoma plc announced today that it has signed an asset purchase agreement with Advanced Cancer Therapeutics for its entire interest in its aptamer AS1411.

Antisoma will receive USD 50 thousand upfront and if AS1411 is approved and commercialised, Antisoma will receive royalties, between 3 to 5 per cent, on AS1411 sales.

Due to testing being discontinued on AS1411 in January 2011, the interim accounts to 31 December 2010 acknowledged that any intangible asset held in respect of AS1411, would require impairment to nil.

The sale of AS1411 may be subject to shareholder approval. The Company will make a further announcement should this be the case.

Enquiries:

Eric Dodd, Company Secretary +44 (0) 203 249 2127

Antisoma plc

About AS1411

AS1411 has shown activity against a range of solid and blood cancer cell lines in preclinical experiments and could therefore have potential against a variety of human cancers.AS1411 is an aptamer. This is a type of drug based on a short piece of DNA or RNA. However, unlike some other drugs based on these chemicals, aptamers work as conventional drugs, binding to a protein target by virtue of a fit with its three-dimensional structure. The term aptamer is derived from the Greek 'aptos' (to fit).

AS1411 has a structure that allows it to bind specifically to a protein called nucleolin, which is found on the surface of many cancer cells. Once bound, the AS1411 aptamer is taken into the cancer cell, where it causes death by apoptosis (programmed cell death).