Xoma Corp. has developed antibody fragments that can begenetically engineered in large enough quantities to be acheaper, commercially viable alternative to monoclonalantibodies made in animal cells.

At this week's meeting of the American Chemical Society inNew York, Xoma researcher Marc Better showed that theportion of antibodies that bind to medically important targets,called the Fab and Fab2 antibody regions, can be cloned andexpressed in E. coli bacteria, and the fermentation productioncan be scaled up to commercially relevant levels.

"We have been able to increase expression 600- to 700-fold,"Better told BioWorld. "We can make large quantities quiteeasily."

The fragments are also being linked to ricin to deliver thisplant toxin to target cells in autoimmune diseases.

This is the second generation of immunoconjugates for immunesystem disorders that the Berkeley, Calif., company isdeveloping, said spokeswoman Carol DeGuzman. "We are stilllooking at which autoimmune diseases will be the targets."

In June, Xoma (NASDAQ:XOMA) received an approvalrecommendation from a Food and Drug Administration advisorycommittee for its anti-CD5 monoclonal linked to ricin. TheMAb would treat steroid-resistant graft-vs.-host disease, acomplication of bone marrow transplants.

The antibody fragment approach should yield "virtuallyunlimited quantities at low cost compared to whole (CD5-ricin) antibodies that you need to make in mice," Better said.

-- Roberta Friedman, Ph.D. Special to BioWorld

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