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04/09/2008

Antisoma starts phase II trial of AS1411 in renal cancer

London, UK: 04 September 2008 – Cancer drug developer Antisoma plc(LSE: ASM; USOTC: ATSMY) today announced that it has started a phase II study of AS1411 in metastatic renal cell carcinoma (kidney cancer).

The single-arm trial will enrol around 30 patients intolerant to, or having relapsed after, previous treatments including a tyrosine kinase inhibitor (sunitinib or sorafenib). It will evaluate the safety and efficacy of AS1411 monotherapy given at 40 mg/kg/day for four days every 28 days for up to two cycles. Efficacy measures in the trial include response rates, time to progression and progression-free survival. Final results are expected in 2010.

Dr Jonathan Rosenberg of the Dana-Farber/Harvard Cancer Center, Boston, MA, an investigator in the trial, said:"AS1411 showed an excellent safety profile and promising signs of activity in renal cell carcinoma patients in phase I testing, and so we’re delighted to be involved in further evaluating its potential in this setting. While a number of new therapies are now available, advanced kidney cancer remains an incurable illness in the large majority of patients, and there is still a clear unmet need to improve treatments available to these patients."

The phase I trial of AS1411 included 12 patients with renal cell carcinoma. Eleven showed at least stabilisation of their disease. Of these, two had objective responses, including one complete response. A phase II trial of AS1411 in acute myeloid leukaemia was initiated last year and recently reported promising preliminary findings.

Antisoma’s Chief Executive Officer, Glyn Edwards, commented: “Evidence to date suggests that AS1411 has broad potential against blood cancers and solid tumours. With phase II trials now ongoing in both acute myeloid leukaemia and kidney cancer, we are testing AS1411 in diverse settings, and look forward to the roll-out of clinical data over the next two years.”

Enquiries:

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:

Background on the AS1411 phase II trial in kidney cancer
Additional details of the phase II trial of AS1411 will be available shortly at www.clinicaltrials.gov.

Background on AS1411
Aptamers are short pieces of DNA or RNA that can fold into stable, three-dimensional structures capable of interacting with particular target proteins. AS1411 is the first aptamer to be tested as a treatment for cancer. It binds to the protein nucleolin, which is found on the surface of cancer cells. It is then internalised and has been shown to kill cancer cells from a variety of cell lines. The drug has also shown anti-cancer effects in animal models and promising signs of anti-cancer activity in the clinic. AS1411 was originally developed by Dr Paula Bates, Dr John Trent and Prof. Donald Miller at the University of Alabama and then at the University of Louisville. Antisoma added AS1411 to its pipeline when it acquired the Louisville-based company Aptamera Inc. in February 2005. AS1411 is now in phase II clinical trials in acute myeloid leukaemia (AML) and renal cell carcinoma (RCC).

Background on Antisoma
Antisoma is a London Stock Exchange-listed biopharmaceutical company that develops novel products for the treatment of cancer. The Company has operations in the UK and the US. Please visit www.antisoma.com for further information about Antisoma.