A chemoenzymatic approach toward the preparation of site-specific antibody-drug conjugates

An efficient chemical synthesis of UDP-N-azidoacetylgalactosamine (UDP-GalNAz) is presented, while the value of this molecule was demonstrated through its attachment to an antibody Fc domain. Thus, the antibody was first degalactosylated, which was followed by loading of the UDP-GalNAz with a recombinant galactosyltransferase. This engineered Azide-Fc-N-glycan antibody was subsequently 'clicked' by a strain-promoted alkyne-azide cycloaddition reaction for site-specific attachment of a fluorescent probe. The principles detailed will allow for the facile preparation of chemically defined homogeneous antibody-drug conjugates (ADCs). (C) 2014 Elsevier Ltd. All rights reserved.