Phage Display Patent Granted to Cambridge Antibody Technology

Cambridge Antibody Technology (CAT; Melbourne, England) has been granted a U.S. patent for the display of antibody fragments on phage (the "McCafferty" patent). Patent number US 5,969,108 entitled "Methods for Producing Members of Specific Binding Pairs," further strengthens CAT's intellectual property position in the field of phage antibody display. It provides protection in the US for the CAT Library—an extensive phage display antibody library—and for the therapeutic antibody products derived from it that are being developed by CAT and its collaborative partners.

The McCafferty patent has claims relating to phage displaying a single chain Fv fragment ("scFv") on its surface, host cells harboring libraries of phage displaying scFvs, scFvs isolated from such libraries, and antibody products constructed from these. The patent arises from work carried out by the Medical Research Council and CAT. Similar patents have already been granted to CAT in Europe, Australia, and South Korea.

The CAT Library incorporates around 100 billion phage antibodies, each incorporating a different antibody gene, and hence displays a different antibody. To isolate antibodies to a target molecule the entire library is incubated with the molecule. The relatively few phage antibodies which bind that protein target remain attached while the remaining billions which do not bind that specific target are washed away. As the phage antibody contains the genes that code for the antibody protein, the genes can be recovered and used in the development and potential manufacture of an antibody therapeutic product. This whole process takes less than a week from start to finish, speed unmatched in other approaches to antibody isolation.

The library forms the basis for the company's strategy to develop a portfolio of clinical development programs and for discovering new drug leads using functional genomics. The CAT Library is in use in the research laboratories of three major biopharmaceutical companies in addition to CAT's own laboratories, where research collaborations with a further five companies are taking place.

David Chiswell, CEO of CAT, commented: "The McCafferty patent adds to CAT's growing US patent estate covering the phage display of antibodies. The US patent portfolio now includes patents covering the display of antibodies on phage (McCafferty et al) and the isolation of human antibodies to human proteins or other antigens by phage display (Griffiths et al). Taken together with CAT's other patents granted worldwide, the granting of this patent underscores the strengths of CAT's patent position and confirms CAT's leadership in the development of human antibodies."

For more ifnormation: David Chiswell, CEO, Cambridge Antibody Technology Group, The Science Park, Melbourn, Cambridgeshire, SG8 6JJ, UK. Tel: +44 1763-263-233. Fax: +44 1763-263-413.

Edited by Laura DeFrancesco