Chemically Crosslinked Bispecific Antibodies for Cancer Therapy: Breaking from the Structural Restrictions of the Genetic Fusion Approach

Chemical and Enzymatic Methods for Post-Translational Protein-Protein Conjugation

Fusion proteins play an essential role in the biosciences but suffer from several key limitations, including the requirement for N-to-C terminal ligation, incompatibility of constituent domains, incorrect folding, and loss of biological activity. This perspective focuses on chemical and enzymatic approaches for the post-translational generation of well-defined protein-protein conjugates, which overcome some of the limitations faced by traditional fusion techniques. Methods discussed range from chemical modification of nucleophilic canonical amino acid residues to incorporation of unnatural amino acid residues and a range of enzymatic methods, including sortase-mediated ligation. Through summarizing the progress in this rapidly growing field, the key successes and challenges associated with using chemical and enzymatic approaches are highlighted and areas requiring further development are discussed.

Generation of bispecific antibodies using chemical conjugation methods

Bispecific antibodies combine the specificity of two antibodies into one molecule. During the past two decades, advancement in protein engineering enabled the development of more than 100 bispecific formats, three of which are approved by the FDA for clinical use. In parallel to protein engineering methods, advancement in conjugation chemistries have spurred the use of chemical engineering approaches to generate bispecific antibodies. Herein, we review selected chemical strategies employed to generate bispecific antibodies that cannot be made using protein engineering methods.