Fusion Proteins with Improved PK

Small recombinant antibody formats are rapidly cleared from circulation. The coupling of these molecules to human serum albumin (HSA) is an efficient strategy to prolong their in vivo half-life. Two methods are described in this chapter for the attachment of HSA to small antibody molecules: the direct fusion of HSA and the indirect coupling by the fusion of an albumin-binding domain to the antibody. Furthermore, an assay is described to verify the functionality of the albumin-binding domain, and a method is proposed to determine the antibodies serum half-life in mice.