BioWorld International Correspondent

LONDON - Antisoma plc is acquiring the private company Aptamera Inc. in an all-share deal that values the U.S. cancer specialist at £11.5 million (US$21.5 million).

The deal gives Antisoma access to AGRO100, an aptamer drug in Phase I, which has FDA orphan drug status in pancreatic cancer. Glyn Edwards, CEO, told BioWorld International the move leapfrogs Antisoma into a lead position in a novel field of cancer drugs.

"This is a really exciting product in a really exciting area," he said. "We want to keep our focus on cancer, but we want to get into different areas. Aptamera will expand our clinical portfolio to four drugs, each based on a very different technology."

London-based Antisoma will issue 66.5 million shares to acquire Aptamera, representing 20 percent of the enlarged share capital. Antisoma shares fell 0.25 pence to 17 pence on Monday when the acquisition was announced.

Aptamera, which was formed in 2001, was looking for venture capital to fund Phase II trials when Antisoma approached the Louisville, Ky.-based firm for rights to AGRO100.

"They weren't looking to out-license, but we went to see them and said, Why not consider an acquisition? That way the product gets developed and the shareholders get liquidity sooner," Edwards said.

Aptamera operates as a virtual company with most research carried out at the James Graham Brown Cancer Center at the University of Louisville.

"[Aptamera] will continue to manage the clinical trial program, but with a lot more support from us," Edwards said. "We will then decide if we are going to switch it to London, or set up a clinical and regulatory office in the U.S."

Mark Rogers, chairman of Aptamera, will become a nonexecutive director of Antisoma.

Antisoma intends to develop AGRO100 independently of its alliance with F. Hoffmann-La Roche Ltd., of Basel, Switzerland, signed in November 2002. "This was a joint decision with Roche. We wanted it to be outside the relationship, and they agreed to waive option rights, though they could opt in later," Edwards said.

Apart from pancreatic cancer, AGRO100 has shown good activity in renal cancer and acute myeloid leukemia in the Phase I trial, and Antisoma now is weighing which indication to focus on for Phase II.

"[Aptamera] was really constrained for cash and got a bit narrow," Edwards said. "The Phase I has not technically closed, and we could add more patients, make it a Phase I/II and get efficacy data."

Aptamers are made up of short sequences of nucleotides that are modified so they fold into a stable 3-dimensional structure. They can be designed to interact with particular proteins, and AGRO100 binds to nucleolin, a protein that is found in the nucleus of all cell types, but also is expressed on the cell surface of a variety of different tumors. After binding, the nucleolin/aptamer complex passes through the cell wall, and within 48 hours the cells begin to accumulate in the S phase of the cell cycle, leading to the induction of apoptosis.

Aptamera has patents on nucleolin, and Antisoma will get an option to license small-molecule mimetics of AGRO100 and monoclonal antibodies targeting nucleolin from the University of Louisville.

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