Antisoma announces positive phase I data on AS1411, plans phase II trials in renal and blood cancers

London, UK, and Istanbul, Turkey, 2 October 2006 - Antisoma today announces the presentation of positive phase I results for its aptamer drug AS1411. Findings in renal cancer are particularly strong. Antisoma will therefore proceed to a phase II trial in this indication. Antisoma will also initiate a phase II trial in a blood cancer indication. Both trials are expected to start in 2007.

The phase I trial of AS1411 initially recruited patients with various cancers. During 2005, it was extended to recruit additional patients with renal and lung cancers.

Twelve renal cancer patients were treated. All had advanced, metastatic disease and most had failed prior treatments. Nine (75%) showed clinical benefit, with seven having stable disease for two months or more and two (17%) having objective responses. These are very encouraging results for patients with this stage of disease.

Updated details of the two responses are as follows:

* One patient was enrolled with a 19 cm abdominal tumour, having already been treated in a clinical trial of another drug. He received AS1411 and was reported to show a near-complete response. A recent biopsy has confirmed the disappearance of the abdominal tumour, making this a complete response. The patient has had a single brain metastasis removed surgically and is free of disease over two years after receiving AS1411.
* A second patient was enrolled with cancer that had spread to both lungs, the liver and lymph nodes, and whose tumours totalled some 20cm in size. He had relapsed after treatment with Gemzar TM , IL2 and interferon plus Avastin TM . Following treatment with AS1411, the patient experienced a partial response, with around 70% tumour shrinkage overall at the latest assessment. One lung tumour and the liver tumour have disappeared and this patient continues to be followed up nine months after treatment.

Five lung cancer patients were treated, two of whom showed stable disease for two months or more. AS1411 was well tolerated up to the maximum dose tested in both renal and lung cancers, with no serious adverse events related to treatment.

The data were presented yesterday at the European Society of Medical Oncology (ESMO) meeting in Istanbul by Professor Donald Miller, Director of the Brown Cancer Center in Louisville, Kentucky, where the trial was conducted. The poster is available on Antisoma’s website at www.antisoma.com.

Commenting on the phase I data, Professor Miller said: “We’re very excited by the findings from this trial of AS1411, particularly the near complete absence of side effects and compelling signs of anti-tumour effects in renal cancer.”

Glyn Edwards, Antisoma’s CEO, said: “With this positive data behind us, we are ready for efficacy studies and intend to push AS1411 forward rapidly through parallel trials in renal and other cancers.”

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.

Gemzar is a trademark of Eli Lilly and Company; Avastin is a trademark of Genentech, Inc.

Notes for Editors:
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 (see release for latest developments). 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.

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. Please visit www.antisoma.co.uk for further information about Antisoma.

Contact Information

Daniel Elger

Director of Communications

Antisoma plc

Contact via E-mail