Chemoenzymatic Conjugation Of Toxic Payloads To The Globally Conserved N‑Glycan Of Native mAbs Provides Homogeneous And Highly Efficacious Antibody−Drug Conjugates

By Remon van Geel, Marloes A. Wijdeven, Ryan Heesbeen, Jorge M. M. Verkade, Anna A. Wasiel, Sander S. van Berkel, and Floris L. van Delft

Random payload conjugation to lysine or cysteine residues produces heterogeneous ADCs with suboptimal therapeutic indices, a limitation well-documented for marketed products.

This peer-reviewed research from van Geel, Wijdeven, and colleagues at SynAffix presents an alternative: a chemoenzymatic protocol that converts native, non-engineered mAbs into homogeneous DAR2 ADCs by targeting the conserved N-glycan at asparagine-297. The two-stage process trims glycan heterogeneity enzymatically, installs a single azide per heavy chain, then ligates payload via copper-free click chemistry using bicyclononyne (BCN). Notably, BCN outperformed DBCO in conjugation efficiency and aggregate formation, and fluorinated azide substrates further accelerated reaction kinetics. In vivo efficacy data from a PDX xenograft model showed sustained tumor regression with glycan-conjugated ADCs compared to a randomly conjugated benchmark at equivalent dosing, despite the lower DAR. A site-scanning study confirmed the native glycosylation site as the preferred conjugation locus.

Explore the full research to examine the methodology, comparative efficacy data, and chemistry underpinning this approach.