LONDON - Human monoclonal antibody specialist Cambridge Antibody Technology Group plc has agreed to buy the U.S. company Aptein Inc. for up to US$11 million in stock.

Aptein has only one employee and Cambridge Antibody does not intend to maintain the company's Seattle office and laboratory. Instead, Royston, U.K.-based Cambridge Antibody wants control of Aptein's polysome display technology, which it believes will provide a powerful extension to its own phage display platform.

John Aston, Cambridge Antibody's finance director, told BioWorld International his company decided to buy Aptein rather than license the technology because “acquiring the technology has different ramifications. It gives us control over its use and exploitation. We want to own it because of the way in which it fits in with our expertise in phage display.“

Cambridge Antibody said the combination of Aptein's polysome display with phage display will improve efficiency through larger library size and faster selection time, enhance its capabilities in antibody-mediated rapid gene cloning and consolidate Cambridge Antibody's dominant position in display technology.

Whereas Cambridge Antibody's platform technology involves the display of large libraries of antibodies on a phage, in Aptein's polysome technology the antibodies are displayed on a ribosome. The complex of a ribosome, messenger RNA and a newly made protein is known as a polysome.

As with phage display, various selection techniques can be used either to isolate single molecules that bind drug targets or to isolate the targets themselves from the library.

“We have been looking at polysome display technology for some time. Aptein is not the only company working on it, but it has got a very good patent position,“ Aston said.

Aptein Patents Free Of Prior Commitments

Although Aptein has had discussions with potential licensees, it has not signed any agreements. Its U.S. patents were granted in 1997 following interference disputes, and its European patents are expected to be granted soon.

Cambridge Antibody will develop the Aptein technology in house. “We need to work out exactly what to do with it in terms of use,“ said Aston. “It can be looked at as an extension of phage display and gives us an alternative means of generating antibody libraries, and potentially gives us richer information.“

Phage display can generate compound libraries up to 1012 in size; ribosome libraries start at 1012 and go up.

The acquisition will take place in two stages. Cambridge Antibody will issue 1.29 million shares totaling US$6 million of the purchase price upon closing the transaction. The balance of up to US$5 million in stock is conditional on issuance of European patents. The number of shares will be determined by the nature of the patent grant. The European patent is expected to be issued shortly, so if there is no opposition, the second stage of the deal could be completed in about a year's time.

“While Aptein has only one employee, it has a number of shareholders, and there has got to be a shareholders' meeting to approve the deal,“ Aston said, adding a majority has indicated it supports the acquisition. He expects the deal to be closed on July 15.

Cambridge Antibody's share price fell by £0.10 to £2.52 when the deal was disclosed last week.

Aptein's founder, Glenn Kawasaki, who set up the company in 1989, will resign when the deal closes but will work as a consultant to Cambridge Antibody. As of Dec. 31, 1997, Aptein had net assets of $234,000 and reported a loss of $94,000 for last year. *