Production of Bispecif ic and Trispecific F(ab)2 and F(ab)3 Antibody Derivatives

Bispecific antibodies (BsAbs) are hybrid molecules designed to combine two antibodies with different specificities. This dual specificity has led to their application in a variety of diagnostic situations that require the crosslinking of two protein surfaces, for example, antigen and detecting agent in lmmunohis-tochemistry or immunoassays. More interestingly, BsAbs have been shown to have considerable therapeutic potential when used as targeting reagents to deliver pharmacological substances (drugs or toxins) or cellular effectors (T-cells, monocytes, or NK cells) to tumor cells (1 ,2 ). A relatively new development is the design of BsAbs to deliver chelated radiometals for the diagnostic imaging of tumors and for radioimmunotherapy (1 ).