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21/01/2002

Positive in vivo results for Antisoma’s cancer drug DMXAA in combination with chemotherapy

London, UK: Antisoma plc (LSE:ASM, NASDAQ-Europe:ASOM), the UK-based biopharmaceutical company specialising in the development of drugs to treat cancer, today announces positive pre-clinical results for the treatment of solid tumours with DMXAA when used in combination with chemotherapy agents.

The studies were undertaken by the University of Auckland, New Zealand, to examine the effect of combining a single dose of DMXAA with single doses of nine widely-used chemotherapy agents in solid tumour in vivo models. Neither DMXAA nor the chemotherapy drugs alone provided prolonged delays in tumour growth or cures. However, co-administration with DMXAA produced a significant delay in tumour growth for eight of the nine chemotherapy drugs. The greatest effect was seen with the chemotherapy agents Taxol® and Taxotere®. In the combination of DMXAA with Taxol®, a median tumour growth delay of 29.5 days was observed and four of the eleven mice treated were cured. The dose of Taxol® used, which was less than the maximum tolerated dose, by itself had no significant activity on the tumour with a median tumour growth delay of 0.3 days and no cures. In the group treated with DMXAA alone, a median growth delay of 10 days was seen and one of the seven mice treated was cured.

In the light of these findings, Antisoma plans to start a clinical study with DMXAA in combination with chemotherapy by the end of this year, following completion of a small dose-finding study in patients.

DMXAA is a small molecule that selectively restricts the blood flow through existing tumour blood vessels that feed tumour growth. DMXAA also appears to cause the endothelial cells lining the blood vessels to release substances that may sensitise tumours to chemotherapeutic agents. The product has already completed two Phase I studies where it was given by itself. It is Antisoma’s intention to develop DMXAA in combination with chemotherapy for a variety of different solid tumours.

Commenting on the results, Glyn Edwards, Chief Executive Officer of Antisoma, said: "These highly encouraging results show that DMXAA has the potential to improve the efficacy of cancer treatment when used in combination with many of today’s chemotherapy regimes. We believe that this drug may have a significant market potential in the treatment of a wide variety of solid tumours."

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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 to Editors

Antisoma
Antisoma is a biopharmaceutical company developing novel products for the treatment of cancer. Using its drug development experience, the Company aims to produce safer and more effective tumour targeting therapies for commercialisation by pharmaceutical partners. Antisoma acquires the rights to promising new product candidates through partnerships with internationally recognised academic or cancer research institutions. These include the lead product candidate, pemtumomab, which was licensed from the Imperial Cancer Research Fund and is currently in a Phase III study as adjuvant treatment for ovarian cancer, with designated Orphan Drug status in the US and EU. There are three additional products in the clinical pipeline, Therex, DMXAA and TheraFab, and several pre-clinical programmes of which two, Angiomab and Thioplatin, are expected to enter clinical studies in 2002. Visit www.antisoma.com for further information about Antisoma.

DMXAA
DMXAA was discovered by Professors Bruce Baguley and William Denny and their teams at the Auckland Cancer Society Research Centre ("ACSRC"), University of Auckland, New Zealand. Phase I human clinical trials have provided safety data and indicate that DMXAA causes a reduction in tumour blood flow when used alone. In extensive studies in animal models, DMXAA used in combination with a number of other anti-cancer agents – particularly taxanes – has been found to control tumour growth. These results have been submitted for peer reviewed publication. Antisoma intend to test DMXAA in combination with chemotherapy.

Cancer Research Ventures (CRV)
DMXAA was in-licensed from Cancer Research Ventures Limited (CRV). CRV is a technology transfer and development company established by The Cancer Research Campaign in the UK to provide technology transfer services to cancer researchers on a worldwide basis. CRV, and its forerunner CRCT, have been providing these services to UK researchers since 1987 and have recently expanded the business into Europe and further afield through the affiliate company Biotech Research Ventures in Singapore. CRV has been instrumental in establishing a number of successful biotech companies in the UK.