Aptamera's Shareholders Approve Acquisition by Antisoma

Antisoma evaluating development options for aptamer drug and servicing of American investors


LONDON and LOUISVILLE, Ken., Feb. 3, 2005 (PRIMEZONE) -- Cancer drug developer Antisoma plc (LSE:ASM) announces that the shareholders of Aptamera Inc yesterday approved Antisoma's acquisition of Aptamera. All pre-closing conditions have now been satisfied or waived, save for admission to the Official List and to trading on the London Stock Exchange of the shares issued to effect the acquisition. Admission of the shares and completion of the transaction are expected tomorrow, 4 February.

Antisoma is evaluating options for the further development of Aptamera's lead product, AGRO100, which is now redesignated AS1411. The next step will be either a phase II study in a specific cancer or the re-opening of Aptamera's phase I trial to seek further data on the drug's effects. Anti-cancer activity has been seen in Aptamera's trial, which also showed that AS1411 was well tolerated, causing no serious adverse events in any of the patients treated.

Antisoma has highlighted renal cancer, pancreatic cancer and acute myeloid leukemia as the indications where the case for developing AS1411 is strongest. Each of these cancers alone represents an attractive 'niche' market opportunity; all have a clear need for improved treatment. Taking these indications together, Antisoma estimates that there could be 170,000 eligible patients per year in North America, Europe and Japan.

Following the acquisition of Aptamera, Antisoma will have around 30% of its shares held by investors in North America. The Company is considering how best to serve the specific needs of these investors in the future.

Glyn Edwards, CEO of Antisoma said, "We intend to identify the best and fastest way to test the anti-cancer efficacy of AS1411, building on the very promising data from Aptamera's first clinical trial. The acquisition of Aptamera leaves us with four drugs in clinical trials, all of which we expect to report important data during 2005."

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

Background on Aptamera

Aptamera is a privately held drug development company based in Kentucky, USA. Aptamera was formed to discover, develop and commercialise new anti-cancer drugs that use a completely new and unique mechanism of anti-tumour action. The drugs target a protein termed nucleolin, which is found in the nucleus of all cell types, but is also found on the cell surface of cancer cells. Aptamera's core intellectual property surrounds cell-surface nucleolin as an anti-proliferative target and drugs that bind to it. Extensive preclinical testing has demonstrated a clear correlation between the presence of cell-surface nucleolin and the ability to inhibit tumour cell growth using Aptamera drugs.

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 November 2002, Antisoma formed a broad strategic alliance with Roche to develop and commercialise products from Antisoma's pipeline. Please visit www.Antisoma.com for further information about Antisoma.

Aptamers

AS1411 (formerly AGRO100) is a member of a class of drugs called aptamers. Aptamers are drugs made up of a short sequence of nucleotides -- the building blocks found in DNA and RNA, that fold into a stable three-dimensional structure. Structures can be produced that interact with particular proteins, allowing aptamers to be used as specific inhibitors of a protein's function. In December 2004, Eyetech and Pfizer's Macugen for 'wet' age-related macular degeneration (AMD) became the first aptamer drug to receive approval from the US Food and Drug Administration.



            

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