By Randall Osborne

Capitalizing on its fusion proteins for use with red blood cell microspheres designed to carry molecules or genes to disease targets, Seragen Inc. signed a licensing agreement with DiagnoCure Inc. to develop cancer therapies.

Seragen, of Hopkinton, Mass., makes fusion proteins of three parts: a probe, which binds to the cell's surface; a syringe-like part that allows insertion of the fusion protein into the cell membrane; and a third part that eliminates the target cell.

Parts of the fusion protein can be used separately, together or with other entities engineered to fit. That's where DiagnoCure, of Quebec City, comes in, said Jean Nichols, president and chief technology officer of Seragen.

"The concept is not complex," she said. "They have a delivery technology that they want to use as a delivery vesicle, and they need a way to target those vesicles."

DiagnoCure's delivery technology consists of microspheres, also known as nanoerythrosomes. A fragmented red blood cell produces about 6,000 of them, much smaller than the red blood cell and therefore able to travel easily within the body with their cargo of bioactive agents.

Under terms of the deal, DiagnoCure will fuse various monoclonal antibodies to replace the probe portion of Seragen's protein, and insert the newly created fusion proteins into the membranes of its microspheres, using the syringe part of the protein.

The microspheres, thus bound to the monoclonal antibodies, could be selectively aimed at delivering their therapeutic contents to targeted cancer cells without harming healthy ones.

Once the nanoerythrosome — which because of its origin is not recognized by the immune system as foreign — binds to the cells, they are absorbed and broken down, transferring their molecular loads to the cell.

"[DiagnoCure] has an interest in genito-urinary tract tumors, so that's going to be the first area," Nichols said.

"It's the exploration of a new application, using parts of fusion proteins as a delivery vehicle in combination with a polymer," Nichols said. "It's a whole area where we have a family of patents, but have not been able to exploit them."

At the same time, the deal with DiagnoCure does not involve Seragen's core patents related to the making of fusion proteins, Nichols said, so the company is not giving up much.

"In fact, nothing," she said. "That's why it's so good for us."

Last December, Seragen filed its first biologics license application with the FDA for Interleukin-2 Fusion Protein to treat recurrent or persistent cutaneous T cell lymphoma. (See BioWorld Today, Dec. 10, 1997, p. 1.)

Seragen's stock (OTC Bulletin Board:SRGN) closed Thursday at $0.68, down $0.02. *

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