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

Area of Science:

• Bioconjugation Chemistry
• Antibody Engineering
• Drug Delivery Systems

Background:

• Site-specific chemical modification of native antibodies is challenging.
• Existing ligand-directed conjugation methods often require multiple steps for ligand removal and payload attachment.

Purpose of the Study:

• To develop a facile, one-step strategy for synthesizing site-specific antibody-drug conjugates (ADCs).
• To enable precise toxin assembly onto native antibodies while simultaneously releasing the targeting ligand.

Main Methods:

• Utilized a novel thioester-based acyl transfer reagent incorporating an Fc-targeting ligand and a toxin payload.
• Developed a traceless conjugation strategy for direct assembly of toxins onto the K251 position of native IgGs.
• Synthesized K251-linked ADCs using native Trastuzumab.

Main Results:

• Achieved facile and efficient one-step synthesis of site-specific ADCs.
• Demonstrated precise toxin assembly at the K251 position of IgGs.
• Synthesized homogeneous ADCs with excellent thermal stability and potent in vitro and in vivo anti-tumor activity.
• Confirmed efficacy across IgG1, IgG2, and IgG4 subtypes.

Conclusions:

• The novel traceless strategy enables efficient one-step synthesis of site-specific ADCs.
• This method offers a simplified and effective approach for antibody modification and drug delivery.
• The developed ADCs show promising therapeutic potential for anti-tumor applications.