Antisoma’s phase II study of AS1404 in ovarian cancer completes recruitment

London, UK: 20 March 2006 – Cancer drug developer Antisoma plc (LSE: ASM; USOTC: ATSMY) today announces that it has completed recruitment of patients into its phase II trial of AS1404 in ovarian cancer. This keeps the Company on course to report data from this trial during 2006.

Antisoma is currently conducting three separate phase II trials with AS1404 in lung, prostate and ovarian cancers. All evaluate the benefit of adding AS1404 to standard chemotherapy treatment.

Antisoma’s CEO, Glyn Edwards, said: “During this year, nearly 100,000 women will be diagnosed with ovarian cancer in Europe, North America and Japan. Many will receive platins and taxanes – drugs whose effects are greatly enhanced when combined with AS1404 in preclinical studies. We are delighted that ovarian cancer patients and physicians in eight countries have worked with us to see whether similar benefits can be achieved in the clinic by combining chemotherapy with AS1404.”

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.

Notes for Editors:

AS1404 ovarian cancer study
This randomised, controlled trial includes around 70 patients from Europe, Australia and New Zealand with platinum-sensitive recurrent ovarian cancer. Half the patients are receiving standard chemotherapy treatment while the other half are receiving the same treatment plus AS1404. The standard chemotherapy regime for these ovarian cancer patients is carboplatin and paclitaxel, the same as in the ongoing lung cancer study. Tumour response rates, time to tumour progression and survival will be compared to see whether patients on the AS1404-chemotherapy combination have better outcomes than those on chemotherapy alone.

Background on AS1404

AS1404 (DMXAA) is a small-molecule vascular disrupting agent which targets the blood vessels that nourish tumours. The drug was discovered by Professors Bruce Baguley and William Denny and their teams at the Auckland Cancer Society Research Centre, University of Auckland, New Zealand. It was in-licensed by Antisoma from Cancer Research Ventures Limited (now Cancer Research Technologies) in August 2001. Preclinical evidence shows that the drug significantly enhances the efficacy of various chemotherapy drugs, complementing their action on tumours. Antisoma’s programme of phase II trials therefore combines AS1404 with established chemotherapy treatments. The programme includes separate randomised, controlled trials in lung, prostate and ovarian cancers. Preliminary findings from the lung cancer trial showed a higher frequency of tumour responses and a lower frequency of progressive disease in those patients receiving AS1404 in addition to chemotherapy.

Background on Antisoma

Based in London, UK, Antisoma is a biopharmaceutical company that develops novel products for the treatment of cancer. Antisoma fills its development pipeline by acquiring promising new product candidates from internationally recognised academic or cancer research institutions. Its core activity is the preclinical and clinical development of these drug candidates. In 2002, Antisoma formed a broad strategic alliance with Roche to develop and commercialise products from Antisoma’s pipeline. AS1404 is one of the products included in this alliance. Please visit www.antisoma.com for further information

Contact Information

Daniel Elger

Director of Communications

Antisoma plc

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