Antibody Humanization via Framework Substitution
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Solution Overview
Problem
Current methods for modifying antibodies to reduce immunogenicity often result in a loss of binding affinity, making them less effective for long-term use in therapeutic applications, especially when administered to species other than humans, such as companion animals or livestock, due to the need for significant structural changes.
Innovation Solution
A method called Parsimonious Essential Translation (PET) is developed, which modifies donor antibodies by substituting only the amino acids in the framework regions that are foreign to the target species, using conservative substitutions to maintain binding affinity and specificity while minimizing immune response, thereby creating non-immunogenic antibodies suitable for administration across species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If chimeric antibody techniques are used to reduce immunogenicity by replacing constant domains with human-derived sequences, then the likelihood of neutralising antibodies being produced is reduced, but the structural complexity and manufacturing complexity increase
Solution Approach 1:
The antibody is divided into functional segments: the variable regions (including CDRs) are retained from the non-human donor antibody to maintain antigen binding specificity, while the constant regions are replaced with human-derived sequences to reduce immunogenicity. This segmentation allows independent optimization of binding function and immunogenicity reduction.
Solution Approach 2:
Different parts of the antibody are given different origins: the antigen-binding variable regions maintain their non-human sequence characteristics to preserve binding affinity, while the constant regions are humanized to reduce immune recognition. This local differentiation resolves the contradiction between maintaining binding function and reducing immunogenicity.
2Object-affected harmful factors
If humanisation techniques such as CDR grafting are employed to reduce immunogenicity, then neutralising antibody production is reduced, but binding affinity is significantly reduced
Solution Approach 1:
The antibody structure is segmented into CDR regions and framework regions. The CDRs are graft ed onto human framework regions, but the framework regions are carefully selected and optimized to maintain the structural context necessary for high-affinity binding. This segmentation allows the CDRs to retain their antigen-specific binding while the human framework reduces immunogenicity.
Solution Approach 2:
The framework regions are not simply replaced but are selected and optimized based on their ability to support high-affinity binding. Parameters such as framework sequence composition, structural conformation, and interaction with CDRs are adjusted to maintain binding affinity while achieving humanization for reduced immunogenicity.
3Object-affected harmful factors
If significant structural changes are made to reduce immunogenicity, then neutralising antibody production is reduced, but the binding specificity and affinity are compromised
Solution Approach 1:
The antibody is segmented such that the antigen-binding site (comprised of CDRs and their immediate framework context) is preserved from the non-human donor to maintain binding specificity, while the immunogenic constant regions are humanized. This segmentation ensures that binding precision is maintained while reducing immunogenicity.
Solution Approach 2:
The humanization is applied locally to specific regions (primarily constant regions and distant framework regions) that do not directly contact the antigen, while the critical antigen-binding CDR regions and their immediate structural context are preserved. This local application of humanization maintains binding specificity while reducing overall immunogenicity.
Data Source
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AI summary
A method of producing a non-immunogenic immunoglobulin for administration to a target species is provided wherein the method comprises substituting amino acid residues in framework regions of a donor immunoglobulin with amino acid residues present at a corresponding position in framework regions of at least one immunoglobulin derived from the target species. Also provided are antibodies produced by the method of the invention, including novel humanised and caninised anti-NGF antibodies. The invention extends to nucleic acids encoding same and to methods of treating pain and arthritis in a human or dog using said antibodies and/or nucleic acids.