Strategy for pre-clinical evaluation of factor VIII concentrates

A series of methods and assay systems was designed, using both mouse monoclonal antibodies and purified human polyclonal antibodies, by which alterations in the antigenic properties, and potentially therefore in the immunogenic properties, of FVIII concentrates could be identified. Those methods could be applied to the pre-clinical evaluation of FVIII concentrates. It has become evident that very subtle alterations in FVIII can have dramatic effects on its antigenicity and immunogenicity and it is suggested that an analysis of FVIII preparations, using reagents such as mouse monoclonal antibodies, should be carried out as a pre-clinical evaluation. It is also thought that any haemophiliac patient is at risk of developing anti-FVIII antibodies, even though he had been considered as tolerant to the infusion of FVIII. The diversity of FVIII concentrates now available on the market has multiplied the chances of encountering a product that would give an immune response in some patients and this further stresses the need for a careful check of FVIII concentrates.