Antibody Disulfide Bond Reoxidation for Homogeneous ADC Loading
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Solution Overview
Problem
Existing methods for site-specific modification of antibodies, such as those used in antibody-drug conjugates (ADCs), suffer from issues like immunogenicity risk, complicated purification, and high cost, leading to heterogeneous mixtures and variable drug-antibody ratios (DAR) that affect efficacy and toxicity.
Innovation Solution
A method involving the use of transition metal ions and reductants to selectively reduce and re-oxidize disulfide bonds in antibodies, followed by conjugation with specific groups, allowing for site-specific modification with minimal conformation change and intact Fc function, compatible with current thiol-reactive linker-drug technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional conjugation methods (lysine or cysteine) are used to attach drug molecules to antibodies, then drug loading can be achieved, but heterogeneous mixtures are produced with variable DAR values affecting efficacy and toxicity
Solution Approach 1:
The patent introduces a peptide tag with a specific conjugation site at the C-terminus of the antibody heavy chain. This creates a localized, unique conjugation site with distinct chemical properties (cysteine residue in the peptide tag), ensuring that drug molecules attach at a specific location rather than distributed across multiple lysine or cysteine residues throughout the antibody structure, thereby achieving homogeneous DAR values
Solution Approach 2:
The peptide tag is预先 fused to the antibody heavy chain C-terminus before conjugation. This preliminary action creates a predetermined conjugation site that directs subsequent drug attachment to a specific location, eliminating the need for complex purification steps to separate heterogeneous conjugates and ensuring consistent DAR values
2Manufacturing precision
If site-specific modification methods (e.g., GlycoConnect, Tub-tag) are used to improve ADC homogeneity, then DAR control is enhanced, but the process becomes more complex with immunogenicity risk, complicated purification, and high cost
Solution Approach 1:
The patent uses a simple peptide tag sequence that can be easily synthesized and fused to the antibody. The tag includes a single cysteine residue for conjugation and is designed to be minimally invasive to antibody function. This simple, disposable-like approach avoids the complexity of enzyme systems (GlycoConnect) or large protein tags (Tub-tag), reducing immunogenicity risk and simplifying purification
Solution Approach 2:
The patent modifies the antibody by adding a short peptide sequence (e.g., GGC-Cys-Gly-Gly-Ser-Lys-Lys) at the C-terminus. This parameter change (adding specific amino acid residues) creates a unique chemical environment for conjugation without fundamentally altering the antibody's core structure or requiring complex enzymatic systems, thereby simplifying the overall process while maintaining homogeneity
3Quantity of substance
If multiple disulfide bonds are reduced to increase conjugation sites, then more drug molecules can be attached, but antibody conformation and Fc function may be compromised
Solution Approach 1:
The patent segregates the conjugation function from the antibody's core structural disulfide bonds. By placing a cysteine-containing peptide tag at the C-terminus (outside the Fc region), the conjugation sites are separated from the critical interchain disulfide bonds that maintain antibody conformation and Fc function. This segmentation allows drug attachment without compromising structural integrity
Solution Approach 2:
The peptide tag acts as an intermediary between the antibody and the drug molecule. It provides a dedicated conjugation interface (cysteine residue) that mediates drug attachment while isolating the antibody's core structure from direct modification. This intermediary protects the antibody's conformational stability and Fc function while enabling controlled drug loading
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances the homogeneity of antibody conjugates, improving safety and curative effects by controlling the drug loading and reducing toxicity, while being cost-effective and simpler to operate without enzyme engineering.
Implementation Method 1
contacting a first reductant or salt thereof and an antibody in the presence of transition metal ions, to reduce at least one of the interchain disulfide bond of the antibody
Implementation Method 2
reduce at least one of the interchain disulfide bond of the antibody
Implementation Method 3
introducing an oxidant to selectively re-oxidize the reduced thiol groups resulted from step (R1)
Data Source
AI summary
The present disclosure relates to a method for programmatically managing antibody disulfide bonds site-specific modification, and the modified antibody prepared by the method and the use of the antibody modification.