Antibody Variable-Region Charge Tuning for Blood Half-Life Control
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Solution Overview
Problem
Existing methods for prolonging the half-life of antibodies in blood primarily focus on modifying the Fc domain, which can lead to antigenicity issues, and modifying the variable regions to control half-life has not been effectively achieved due to the reliance on the Fc receptor binding, neglecting the potential of surface charge modifications in the variable regions.
Innovation Solution
Modifying amino acid residues exposed on the surface of the variable regions of antibodies to control their surface charge, thereby controlling the blood half-life without affecting the antibody structure or function, applicable to polypeptides with an FcRn-binding domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If amino acid substitutions are made in the Fc domain to prolong antibody half-life, then the half-life in blood is prolonged, but the antigenicity increases
Solution Approach 1:
The invention applies local quality by making amino acid substitutions specifically in the variable region (FR or CDR) rather than the Fc domain, and specifically choosing substitutions that alter surface charge properties. This localized modification approach achieves half-life prolongation through charge-mediated mechanisms while preserving the human-like Fc domain structure, thereby reducing antigenicity compared to Fc domain modifications.
Solution Approach 2:
The invention changes physical-chemical parameters (amino acid charge properties) in the variable region to control antibody pharmacokinetics. By substituting amino acids with different charge characteristics (e.g., adding basic residues to increase positive charge or acidic residues to increase negative charge), the invention alters the antibody's interaction with serum components and FcRn, thereby controlling half-life without modifying the Fc domain structure.
2Object-affected harmful factors
If amino acid substitutions are made in the variable region to control half-life, then the half-life control is achieved with lower antigenicity, but the method was previously considered ineffective due to reliance on Fc receptor binding
Solution Approach 1:
The invention introduces surface charge as an intermediary mechanism between the variable region amino acid substitutions and the FcRn binding interaction. By modifying the charge properties of amino acids exposed on the variable region surface, the invention mediates the antibody's interaction with the acidic environment of endosomes and its binding to FcRn, thereby achieving reliable half-life control through a previously unrecognized pathway.
3Duration of action of moving object
If the isoelectric point is changed through modification, then the blood half-life can be controlled, but the antibody structure and function may be affected
Solution Approach 1:
The invention applies local quality by making amino acid substitutions specifically in the framework region or CDR regions of the variable domain, targeting specific locations that expose amino acid side chains to the solvent. These localized substitutions alter the overall isoelectric point and surface charge distribution without disrupting the core antibody structure or antigen-binding function.
Solution Approach 2:
The invention changes the isoelectric point parameter through controlled amino acid substitutions in the variable region, selecting specific amino acid pairs (e.g., adding basic residues like lysine or arginine to increase positive charge, or acidic residues like aspartic acid or glutamic acid to increase negative charge) that shift the pI while maintaining structural stability and biological function.
Data Source
AI summary
The present inventors discovered that the half-life in blood of an IgG antibody which is a polypeptide comprising an FcRn-binding domain can be controlled by controlling the surface charge through modification of residues exposed on the surface among residues in the variable regions of the IgG antibody. Antibodies whose half-life in blood had been controlled by the methods of the present invention were confirmed to actually retain the original activity. The methods of the present invention are widely applicable to polypeptides comprising an FcRn-binding domain, such as IgG antibodies, which are recycled via the FcRn salvage pathway regardless of the type of target antigen.