LONDON - PolyMASC Pharmaceuticals plc formed a research agreement with Bayer Corp.'s pharmaceutical division in Pittsburgh to work on extending the half-life of Bayer's factor VIII blood-clotting factor using PolyMASC's protein modification technology.

A feasibility study will be done to enable Bayer to decide whether to enter into a broader agreement for the commercial development of a chemically modified factor VIII.

Bayer had sales of $400 million in 1998 of Kogenate, its recombinant factor VIII for the prevention of bleeding episodes in patients with hemophilia A. In addition to extending the plasma half-life, the research will look at reducing the antigenicity and immunogenicity of factor VIII. Some hemophilia sufferers cannot be treated with factor VIII due to pre-existing factor VIII inhibitory antibodies.

PolyMASC, of London, has a range of drug formulation and delivery technologies. In this case it will apply its ProtoMASC process for the polymer modification of proteins and peptides. That process extends the half-life of proteins and shields them from the body's immune and clearance mechanisms.