Synthesis of Precision Antibody Conjugates Using Proximity-Induced Chemistry

To produce homogeneous antibody conjugates, antibody engineering or chemical/enzymatic treatments are required, processes that often affect antibody folding and stability, as well as yield and cost. Here, we describe a simple proximity-induced antibody conjugation method (pClick) that enables the synthesis of homogeneous antibody conjugates from native antibodies without requiring additional antibody engineering or post-synthesis treatment. A proximity-activated crosslinker is introduced into a chemically synthesized affinity peptide modified with a bioorthogonal handle. Upon binding to a specific antibody site, the affinity peptide covalently attaches to the antibody via spontaneous crosslinking, yielding an antibody molecule ready for bioorthogonal conjugation with payloads. We have prepared well-defined antibody-drug conjugates and bispecific small molecule-antibody conjugates, exhibiting excellent in vitro cytotoxic activity against cancer cells and superb antitumor activity in mouse xenograft models. This technology does not require antibody engineering or additional UV/chemical/enzymatic treatments, therefore providing a general, convenient strategy for developing novel antibody conjugates.