A Traceless Site-Specific Conjugation on Native Antibodies Enables Efficient One-Step Payload Assembly

Direct chemical modification of native antibodies in a site-specific manner remains a great challenge. Ligand-directed conjugation can achieve the selective modification of antibodies, but usually requires multiple extra steps for ligand release and cargo assembly. Herein, we report a novel, traceless strategy to enable the facile and efficient one-step synthesis of site-specific antibody-drug conjugates (ADCs) by harnessing a thioester-based acyl transfer reagent. The designed reagent, consisting of an optimized Fc-targeting ligand, a thioester bridge and a toxin payload, directly assembles the toxin precisely onto the K251 position of native IgGs and simultaneously self-releases the affinity ligand in one step. With this method, we synthesized a series of K251-linked ADCs from native Trastuzumab. These ADCs demonstrated excellent homogeneity, thermal stability, and both in vitro and in vivo anti-tumor activity. This strategy is equally efficient for IgG1, IgG2, and IgG4 subtypes.

Automated summary

In this paper, a strategy for the facile and efficient one-step synthesis of site-specific antibody-drug conjugates (ADCs) using a thioester-based acyl transfer reagent is reported. This strategy allows for the selective modification of antibodies and demonstrates excellent homogeneity, stability, and anti-tumor activity.