Cancer drug development company Antisoma plc has entered into an agreement to acquire the private US company Aptamera Inc in a share-based transaction valuing Aptamera at approximately £11.5 million ($21.4 million).

Aptamera's principal asset is AGRO100, a novel aptamer drug that has shown promising anti-cancer effects and a marked lack of side effects in a phase I trial of patients with various cancers. Antisoma will now assess which cancers to focus on in the next phase of development. AGRO100 has US orphan drug status in pancreatic cancer. Renal cancer and acute myeloid leukaemia are also potential indications. Antisoma will develop AGRO100 independently, outside its alliance with Roche.

AGRO100 targets nucleolin, a protein found on the surface of many types of cancer cell. The University of Louisville, Kentucky, where AGRO100 was latterly developed, is researching further drugs based on targeting nucleolin. Through its acquisition of Aptamera, Antisoma will obtain an option to license these drugs from the university, release from Antisoma said.

Commenting on the transaction, Glyn Edwards, CEO of Antisoma, said, "The acquisition of Aptamera will expand our clinical portfolio to four drugs, each based on very different technology, and make us a leader in the exciting new area of anti-cancer aptamers. The acquisition will crystallise our dual development and commercialisation strategy, whereby we gain returns from large market products through our alliance with Roche whilst retaining full rights to promising niche products such as Aptamera's AGRO100."

In consideration of Antisoma acquiring the entire issued share capital of Aptamera, Antisoma will issue to Aptamera's shareholders up to 66,500,100 ordinary shares, representing approximately 20.0 per cent of the enlarged issued share capital of Antisoma. Based on Antisoma's closing share price on 7 January 2005 of 17.25 pence, the transaction is valued at £11.47 million.