Discussions

Antibody-functionality conjugates
Chemical conjugation is a versatile strategy that allows the generation of several different formats of BsAbs by using different crosslinkers. The crosslinkers contain several reactive groups, which are used to conjugate the antibody units. Moreover, if there are additional reactive groups, they can be used to incorporate more functionalities, such as fluorophores, simulating peptides, PEG, siRNA, cytotoxic drugs, etc. Different from antibody-peptide conjugates, in which the antibody portion just acts as a carrier, antibody-functionality conjugates retain the reactivity of antibody moieties and the properties of additional functionalities. The strategy that has been widely used is the PEGylation of proteins. As antibody fragments, the small size of scFv and Fab endows them with several advantages, including better tissue penetration. However, they have a shorter half-life. To overcome this problem, PEGylation is an optional strategy to extend the molecule's half-life and has also been clinically proven in marketed products.